core: add support of modifiers in evaluation of expressions with "modifier:name,data,string" (issue #60)

10 files changed, 148 insertions, 105 deletions

diff --git a/doc/de/autogen/user/weechat_commands.adoc b/doc/de/autogen/user/weechat_commands.adoc
index a2f0ac861..c1cda652e 100644
--- a/doc/de/autogen/user/weechat_commands.adoc
+++ b/doc/de/autogen/user/weechat_commands.adoc
@@ -266,67 +266,68 @@ infolists: zeigt Information über die Infolists an
 /eval  [-n|-s] <expression>
        [-n] -c <expression1> <operator> <expression2>
 
-        -n: gibt das Ergebnis aus, ohne das dieses in den Buffer gesendet wird (debug Modus)
-        -s: teilt Ausdrücke bevor sie evaluiert werden (mehrere Befehle können durch Semikolon getrennt werden)
-        -c: Auswertung als Bedingung: nutzt Operatoren und runde Klammern, Rückgabewert als Boolean-Wert ("0" oder "1")
-expression: Ausdruck welcher verarbeitet werden soll. Variablen im Format ${variable} werden ersetzt (siehe unten); mehrere Befehle werden durch ein Semikolon voneinander getrennt
-  operator: ein logischer oder vergleichender Operand:
-            - logische Operanden:
-                &&  boolean "und"
-                ||  boolean "oder"
-            - vergleichende Operanden:
-                ==  gleich
-                !=  ungleich
-                <=  kleiner oder gleich
-                <   kleiner
-                >=  größer oder gleich
-                >   größer
-                =~  stimmt mit regulärem POSIX Ausdruck überein
-                !~  stimmt NICHT mit regulärem POSIX Ausdruck überein
-                =*  stimmt mit Maske überein (Platzhalter "*" ist erlaubt)
-                !*  stimmt mit Maske NICHT überein (Platzhalter "*" ist erlaubt)
-
-Ein Ausdruck gilt als "wahr" sofern das Ergebnis weder NULL, nicht leer und von "0" abweichend ist.
-Für einen Vergleich werden Fließkommazahlen genutzt sofern es sich bei beiden Ausdrücken um gültige Nummer handelt, folgende Formate werden unterstützt:
-  - Integer (Beispiele: 5, -7)
-  - Fließkommazahl (Beispiele: 5.2, -7.5, 2.83e-2)
-  - hexadezimale Zahl (Beispiele: 0xA3, -0xA3)
-Um einen Vergleich zwischen zwei Zeichenketten zu erzwingen, müssen die Ausdrücke in Anführungszeichen gesetzt werden, zum Beispiel:
+        -n: display result without sending it to buffer (debug mode)
+        -s: split expression before evaluating it (many commands can be separated by semicolons)
+        -c: evaluate as condition: use operators and parentheses, return a boolean value ("0" or "1")
+expression: expression to evaluate, variables with format ${variable} are replaced (see below); many commands can be separated by semicolons
+  operator: a logical or comparison operator:
+            - logical operators:
+                &&  boolean "and"
+                ||  boolean "or"
+            - comparison operators:
+                ==  equal
+                !=  not equal
+                <=  less or equal
+                <   less
+                >=  greater or equal
+                >   greater
+                =~  is matching POSIX extended regex
+                !~  is NOT matching POSIX extended regex
+                =*  is matching mask (wildcard "*" is allowed)
+                !*  is NOT matching mask (wildcard "*" is allowed)
+
+An expression is considered as "true" if it is not NULL, not empty, and different from "0".
+The comparison is made using floating point numbers if the two expressions are valid numbers, with one of the following formats:
+  - integer (examples: 5, -7)
+  - floating point number (examples: 5.2, -7.5, 2.83e-2)
+  - hexadecimal number (examples: 0xA3, -0xA3)
+To force a string comparison, you can add double quotes around each expression, for example:
   50 > 100      ==> 0
   "50" > "100"  ==> 1
 
-Einige Variablen werden im Ausdruck, mittels der Formatierung ${variable}, ersetzt. Mögliche Variablen sind, nach Reihenfolge ihrer Priorität:
-  1. eine evaluierte Teilzeichenkette (Format: "eval:xxx")
-  2. eine Zeichenkette mit Escapesequenzen (Format: "esc:xxx" oder "\xxx")
-  3. Zeichen welche in einer Zeichenkette nicht dargestellt werden sollen (Format: "hide:Zeichen,Zeichenkette")
-  4. eine Zeichenkette mit einer maximalen Anzahl an Zeichen (Format: "cut:+Max,Suffix,Zeichenkette")
-     oder maximale Anzahl an Zeichen die auf dem Bildschirm angezeigt werden sollen (Format: "cutscr:Max,Suffix,Zeichenkette oder "cutscr:+Max,Suffix,Zeichenkette")
-  5. Ende einer Zeichenkette nutzen (Format: "rev:xxx")
-  6. Wiederholung einer Zeichenkette  (Format: "repeat:Anzahl,Zeichenkette")
-  7. Länge einer Zeichenkette (Format: "length:xxx" oder "lengthscr:xxx")
-  8. eine Farbe (Format: "color:xxx", siehe "Anleitung für API Erweiterung", Funktion "color")
-  9. eine Info (Format: "info:Name,Argumente", Argumente sind optional)
-  10. aktuelles Datum/Uhrzeit (Format: "date" oder "date:format")
-  11. eine Umgebungsvariable (Format: "env:XXX")
-  12. ein Dreifachoperand (Format: "if:Bedingung?Wert_falls_wahr:Wert_falls_unwahr")
-  13. Ergebnis eines Ausdrucks mit Klammern und Operatoren + - * / // % ** (Format: "calc:xxx")
-  14. eine Option (Format: "file.section.option")
-  15. der Name einer lokalen Variablen eines Buffer
-  16. ein hdata Name/Variable (der Wert wird automatisch in eine Zeichenkette konvertiert), standardmäßig wird für "window" und "buffer" das aktuelle Fenster/Buffer verwendet.
-Das Format für hdata kann wie folgt aufgebaut sein:
-  hdata.var1.var2...: startet mit hdata (der Pointer muss bekannt sein) und fragt eine Variable nach der anderen ab (weitere hdata können folgen)
-  hdata[list].var1.var2...: startet hdata mittels einer Liste, zum Beispiel:
-    ${buffer[gui_buffers].full_name}: der vollständige Name des ersten Buffers, in der verknüpften Liste aller Buffer
-    ${plugin[weechat_plugins].name}: Name der ersten Erweiterung, in der verknüpften Liste aller Erweiterungen
-  hdata[pointer].var1.var2...: startet hdata mittels einem Pointer, zum Beispiel:
-    ${buffer[0x1234abcd].full_name}: vollständiger Name eines Buffers und des dazugehörigen Pointers (kann in triggern benutzt werden)
-Die vorhandenen Namen für hdata und Variablen sind in der "Anleitung für API Erweiterung", Bereich "weechat_hdata_get". beschrieben
-
-Beispiele (einfache Zeichenketten):
+Some variables are replaced in expression, using the format ${variable}, variable can be, by order of priority:
+  1. an evaluated sub-string (format: "eval:xxx")
+  2. a string with escaped chars (format: "esc:xxx" or "\xxx")
+  3. a string with chars to hide (format: "hide:char,string")
+  4. a string with max chars (format: "cut:max,suffix,string" or "cut:+max,suffix,string")
+     or max chars displayed on screen (format: "cutscr:max,suffix,string" or "cutscr:+max,suffix,string")
+  5. a reversed string (format: "rev:xxx")
+  6. a repeated string (format: "repeat:count,string")
+  7. length of a string (format: "length:xxx" or "lengthscr:xxx")
+  8. a color (format: "color:xxx", see "Plugin API reference", function "color")
+  9. a modifier (format: "modifier:name,data,string")
+  10. an info (format: "info:name,arguments", arguments are optional)
+  11. current date/time (format: "date" or "date:format")
+  12. an environment variable (format: "env:XXX")
+  13. a ternary operator (format: "if:condition?value_if_true:value_if_false")
+  14. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
+  15. an option (format: "file.section.option")
+  16. a local variable in buffer
+  17. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
+Format for hdata can be one of following:
+  hdata.var1.var2...: start with a hdata (pointer must be known), and ask variables one after one (other hdata can be followed)
+  hdata[list].var1.var2...: start with a hdata using a list, for example:
+    ${buffer[gui_buffers].full_name}: full name of first buffer in linked list of buffers
+    ${plugin[weechat_plugins].name}: name of first plugin in linked list of plugins
+  hdata[pointer].var1.var2...: start with a hdata using a pointer, for example:
+    ${buffer[0x1234abcd].full_name}: full name of the buffer with this pointer (can be used in triggers)
+For name of hdata and variables, please look at "Plugin API reference", function "weechat_hdata_get".
+
+Examples (simple strings):
   /eval -n ${info:version}                       ==> 0.4.3
   /eval -n ${env:HOME}                           ==> /home/user
   /eval -n ${weechat.look.scroll_amount}         ==> 3
-  /eval -n ${sec.data.freenode_password}         ==> geheim
+  /eval -n ${sec.data.freenode_password}         ==> secret
   /eval -n ${window}                             ==> 0x2549aa0
   /eval -n ${window.buffer}                      ==> 0x2549320
   /eval -n ${window.buffer.full_name}            ==> core.weechat
@@ -342,16 +343,16 @@ Beispiele (einfache Zeichenketten):
   /eval -n ${length:test}                        ==> 4
   /eval -n ${calc:(5+2)*3}                       ==> 21
 
-Beispiele (Bedingungen):
-  /eval -n -c ${window.buffer.number} > 2  ==> 0
-  /eval -n -c ${window.win_width} > 100    ==> 1
-  /eval -n -c (8 > 12) || (5 > 2)          ==> 1
-  /eval -n -c (8 > 12) && (5 > 2)          ==> 0
-  /eval -n -c abcd =~ ^ABC                 ==> 1
-  /eval -n -c abcd =~ (?-i)^ABC            ==> 0
-  /eval -n -c abcd =~ (?-i)^abc            ==> 1
-  /eval -n -c abcd !~ abc                  ==> 0
-  /eval -n -c abcd =* a*d                  ==> 1
+Examples (conditions):
+  /eval -n -c ${window.buffer.number} > 2 ==> 0
+  /eval -n -c ${window.win_width} > 100   ==> 1
+  /eval -n -c (8 > 12) || (5 > 2)         ==> 1
+  /eval -n -c (8 > 12) && (5 > 2)         ==> 0
+  /eval -n -c abcd =~ ^ABC                ==> 1
+  /eval -n -c abcd =~ (?-i)^ABC           ==> 0
+  /eval -n -c abcd =~ (?-i)^abc           ==> 1
+  /eval -n -c abcd !~ abc                 ==> 0
+  /eval -n -c abcd =* a*d                 ==> 1
 ----
 
 [[command_weechat_filter]]
diff --git a/doc/en/autogen/user/weechat_commands.adoc b/doc/en/autogen/user/weechat_commands.adoc
index a84d1b074..757f4bae5 100644
--- a/doc/en/autogen/user/weechat_commands.adoc
+++ b/doc/en/autogen/user/weechat_commands.adoc
@@ -305,14 +305,15 @@ Some variables are replaced in expression, using the format ${variable}, variabl
   6. a repeated string (format: "repeat:count,string")
   7. length of a string (format: "length:xxx" or "lengthscr:xxx")
   8. a color (format: "color:xxx", see "Plugin API reference", function "color")
-  9. an info (format: "info:name,arguments", arguments are optional)
-  10. current date/time (format: "date" or "date:format")
-  11. an environment variable (format: "env:XXX")
-  12. a ternary operator (format: "if:condition?value_if_true:value_if_false")
-  13. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
-  14. an option (format: "file.section.option")
-  15. a local variable in buffer
-  16. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
+  9. a modifier (format: "modifier:name,data,string")
+  10. an info (format: "info:name,arguments", arguments are optional)
+  11. current date/time (format: "date" or "date:format")
+  12. an environment variable (format: "env:XXX")
+  13. a ternary operator (format: "if:condition?value_if_true:value_if_false")
+  14. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
+  15. an option (format: "file.section.option")
+  16. a local variable in buffer
+  17. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
 Format for hdata can be one of following:
   hdata.var1.var2...: start with a hdata (pointer must be known), and ask variables one after one (other hdata can be followed)
   hdata[list].var1.var2...: start with a hdata using a list, for example:
diff --git a/doc/en/weechat_plugin_api.en.adoc b/doc/en/weechat_plugin_api.en.adoc
index 4f2b34e08..3f770616d 100644
--- a/doc/en/weechat_plugin_api.en.adoc
+++ b/doc/en/weechat_plugin_api.en.adoc
@@ -2515,6 +2515,15 @@ expanded to last):
   `+red text+` (in red) +
   `+bold orange text+` (in bold orange)
 
+| `+${modifier:name,data,string}+` +
+  (_WeeChat ≥ 2.7_) |
+  Result of a modifier, see function
+  <<_hook_modifier_exec,hook_modifier_exec>>. |
+  `+${modifier:eval_path_home,,~}+` +
+  `+${modifier:eval_path_home,,%h/python}+` |
+  `+/home/xxx+` +
+  `+/home/xxx/.weechat/python+`
+
 | `+${info:name}+` +
   `+${info:name,arguments}+` +
   (_WeeChat ≥ 0.4.3_) |
diff --git a/doc/fr/autogen/user/weechat_commands.adoc b/doc/fr/autogen/user/weechat_commands.adoc
index 5807945f1..f5b5592cb 100644
--- a/doc/fr/autogen/user/weechat_commands.adoc
+++ b/doc/fr/autogen/user/weechat_commands.adoc
@@ -305,14 +305,15 @@ Des variables sont remplacées dans l'expression, en utilisant le format ${varia
   6. une chaîne répétée (format : "repeat:nombre,chaîne")
   7. longueur d'une chaîne (format : "length:xxx" ou "lengthscr:xxx")
   8. une couleur (format : "color:xxx", voir la "Référence API extension", fonction "color")
-  9. une info (format : "info:nom,paramètres", les paramètres sont optionnels)
-  10. la date/heure courante (format : "date" ou "date:format")
-  11. une variable d'environnement (format : "env:XXX")
-  12. un opérateur ternaire (format : "if:condition?valeur_si_vrai:valeur_si_faux")
-  13. le résultat d'une expression avec parenthèses et les opérateurs + - * / // % ** (format: "calc:xxx")
-  14. une option (format : "fichier.section.option")
-  15. une variable locale du tampon
-  16. un hdata/variable (la valeur est automatiquement convertie en chaîne), par défaut "window" et "buffer" pointent vers la fenêtre et le tampon courants.
+  9. un modificateur (format : "modifier:nom,données,chaîne")
+  10. une info (format : "info:nom,paramètres", les paramètres sont optionnels)
+  11. la date/heure courante (format : "date" ou "date:format")
+  12. une variable d'environnement (format : "env:XXX")
+  13. un opérateur ternaire (format : "if:condition?valeur_si_vrai:valeur_si_faux")
+  14. le résultat d'une expression avec parenthèses et les opérateurs + - * / // % ** (format: "calc:xxx")
+  15. une option (format : "fichier.section.option")
+  16. une variable locale du tampon
+  17. un hdata/variable (la valeur est automatiquement convertie en chaîne), par défaut "window" et "buffer" pointent vers la fenêtre et le tampon courants.
 Le format du hdata peut être le suivant :
   hdata.var1.var2... : démarrer avec un hdata (le pointeur doit être connu), et demander les variables l'une après l'autre (d'autres hdata peuvent être suivis)
   hdata[liste].var1.var2... : démarrer avec un hdata en utilisant une liste, par exemple :
diff --git a/doc/fr/weechat_plugin_api.fr.adoc b/doc/fr/weechat_plugin_api.fr.adoc
index 9f9618f60..7e3d7cc63 100644
--- a/doc/fr/weechat_plugin_api.fr.adoc
+++ b/doc/fr/weechat_plugin_api.fr.adoc
@@ -2563,6 +2563,15 @@ première étendue à la dernière) :
   `+texte rouge+` (en rouge) +
   `+texte orange gras+` (en orange gras)
 
+| `+${modifier:name,data,string}+` +
+  (_WeeChat ≥ 2.7_) |
+  Résultat d'un modificateur, voir la fonction
+  <<_hook_modifier_exec,hook_modifier_exec>>. |
+  `+${modifier:eval_path_home,,~}+` +
+  `+${modifier:eval_path_home,,%h/python}+` |
+  `+/home/xxx+` +
+  `+/home/xxx/.weechat/python+`
+
 | `+${info:nom}+` +
   `+${info:nom,paramètres}+` +
   (_WeeChat ≥ 0.4.3_) |
diff --git a/doc/it/autogen/user/weechat_commands.adoc b/doc/it/autogen/user/weechat_commands.adoc
index 57114e6b8..0c052b596 100644
--- a/doc/it/autogen/user/weechat_commands.adoc
+++ b/doc/it/autogen/user/weechat_commands.adoc
@@ -305,14 +305,15 @@ Some variables are replaced in expression, using the format ${variable}, variabl
   6. a repeated string (format: "repeat:count,string")
   7. length of a string (format: "length:xxx" or "lengthscr:xxx")
   8. a color (format: "color:xxx", see "Plugin API reference", function "color")
-  9. an info (format: "info:name,arguments", arguments are optional)
-  10. current date/time (format: "date" or "date:format")
-  11. an environment variable (format: "env:XXX")
-  12. a ternary operator (format: "if:condition?value_if_true:value_if_false")
-  13. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
-  14. an option (format: "file.section.option")
-  15. a local variable in buffer
-  16. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
+  9. a modifier (format: "modifier:name,data,string")
+  10. an info (format: "info:name,arguments", arguments are optional)
+  11. current date/time (format: "date" or "date:format")
+  12. an environment variable (format: "env:XXX")
+  13. a ternary operator (format: "if:condition?value_if_true:value_if_false")
+  14. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
+  15. an option (format: "file.section.option")
+  16. a local variable in buffer
+  17. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
 Format for hdata can be one of following:
   hdata.var1.var2...: start with a hdata (pointer must be known), and ask variables one after one (other hdata can be followed)
   hdata[list].var1.var2...: start with a hdata using a list, for example:
diff --git a/doc/it/weechat_plugin_api.it.adoc b/doc/it/weechat_plugin_api.it.adoc
index 205295ada..8c165937b 100644
--- a/doc/it/weechat_plugin_api.it.adoc
+++ b/doc/it/weechat_plugin_api.it.adoc
@@ -2623,6 +2623,15 @@ expanded to last):
   `+red text+` (in red) +
   `+bold orange text+` (in bold orange)
 
+| `+${modifier:name,data,string}+` +
+  (_WeeChat ≥ 2.7_) |
+  Result of a modifier, see function
+  <<_hook_modifier_exec,hook_modifier_exec>>. |
+  `+${modifier:eval_path_home,,~}+` +
+  `+${modifier:eval_path_home,,%h/python}+` |
+  `+/home/xxx+` +
+  `+/home/xxx/.weechat/python+`
+
 | `+${info:name}+` +
   `+${info:name,arguments}+` +
   (_WeeChat ≥ 0.4.3_) |
diff --git a/doc/ja/autogen/user/weechat_commands.adoc b/doc/ja/autogen/user/weechat_commands.adoc
index fc4eee00d..18c771df3 100644
--- a/doc/ja/autogen/user/weechat_commands.adoc
+++ b/doc/ja/autogen/user/weechat_commands.adoc
@@ -305,14 +305,15 @@ Some variables are replaced in expression, using the format ${variable}, variabl
   6. a repeated string (format: "repeat:count,string")
   7. length of a string (format: "length:xxx" or "lengthscr:xxx")
   8. a color (format: "color:xxx", see "Plugin API reference", function "color")
-  9. an info (format: "info:name,arguments", arguments are optional)
-  10. current date/time (format: "date" or "date:format")
-  11. an environment variable (format: "env:XXX")
-  12. a ternary operator (format: "if:condition?value_if_true:value_if_false")
-  13. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
-  14. an option (format: "file.section.option")
-  15. a local variable in buffer
-  16. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
+  9. a modifier (format: "modifier:name,data,string")
+  10. an info (format: "info:name,arguments", arguments are optional)
+  11. current date/time (format: "date" or "date:format")
+  12. an environment variable (format: "env:XXX")
+  13. a ternary operator (format: "if:condition?value_if_true:value_if_false")
+  14. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
+  15. an option (format: "file.section.option")
+  16. a local variable in buffer
+  17. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
 Format for hdata can be one of following:
   hdata.var1.var2...: start with a hdata (pointer must be known), and ask variables one after one (other hdata can be followed)
   hdata[list].var1.var2...: start with a hdata using a list, for example:
diff --git a/doc/ja/weechat_plugin_api.ja.adoc b/doc/ja/weechat_plugin_api.ja.adoc
index 04b403f96..ce438bb9e 100644
--- a/doc/ja/weechat_plugin_api.ja.adoc
+++ b/doc/ja/weechat_plugin_api.ja.adoc
@@ -2528,6 +2528,16 @@ str5 = weechat.string_eval_expression("password=abc password=def", {}, {}, optio
   `+red text+` (赤色で) +
   `+bold orange text+` (太字オレンジ色で)
 
+// TRANSLATION MISSING
+| `+${modifier:name,data,string}+` +
+  (_WeeChat バージョン 2.7 以上で利用可_) |
+  Result of a modifier, see function
+  <<_hook_modifier_exec,hook_modifier_exec>>. |
+  `+${modifier:eval_path_home,,~}+` +
+  `+${modifier:eval_path_home,,%h/python}+` |
+  `+/home/xxx+` +
+  `+/home/xxx/.weechat/python+`
+
 | `+${info:name}+` +
   `+${info:name,arguments}+` +
   (_WeeChat バージョン 0.4.3 以上で利用可_) |
diff --git a/doc/pl/autogen/user/weechat_commands.adoc b/doc/pl/autogen/user/weechat_commands.adoc
index cdcef73e0..72ebb7dec 100644
--- a/doc/pl/autogen/user/weechat_commands.adoc
+++ b/doc/pl/autogen/user/weechat_commands.adoc
@@ -305,14 +305,15 @@ Some variables are replaced in expression, using the format ${variable}, variabl
   6. a repeated string (format: "repeat:count,string")
   7. length of a string (format: "length:xxx" or "lengthscr:xxx")
   8. a color (format: "color:xxx", see "Plugin API reference", function "color")
-  9. an info (format: "info:name,arguments", arguments are optional)
-  10. current date/time (format: "date" or "date:format")
-  11. an environment variable (format: "env:XXX")
-  12. a ternary operator (format: "if:condition?value_if_true:value_if_false")
-  13. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
-  14. an option (format: "file.section.option")
-  15. a local variable in buffer
-  16. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
+  9. a modifier (format: "modifier:name,data,string")
+  10. an info (format: "info:name,arguments", arguments are optional)
+  11. current date/time (format: "date" or "date:format")
+  12. an environment variable (format: "env:XXX")
+  13. a ternary operator (format: "if:condition?value_if_true:value_if_false")
+  14. result of an expression with parentheses and operators + - * / // % ** (format: "calc:xxx")
+  15. an option (format: "file.section.option")
+  16. a local variable in buffer
+  17. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
 Format for hdata can be one of following:
   hdata.var1.var2...: start with a hdata (pointer must be known), and ask variables one after one (other hdata can be followed)
   hdata[list].var1.var2...: start with a hdata using a list, for example: