Implement maktaba#value#AsList helper to coerce values to a list (#257)

google · Mar 21, 2023 · fe95bb1 · fe95bb1
1 parent 5d416e8
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diff --git a/autoload/maktaba/value.vim b/autoload/maktaba/value.vim
@@ -228,6 +228,19 @@ function! maktaba#value#IsEnum(Value) abort
 endfunction
 
 
+""
+" Coerces {value_or_values} into a list, wrapping any non-list value into a
+" single-item list.
+" Examples: >
+"   maktaba#value#AsList('lonely') == ['lonely']
+"   maktaba#value#AsList(['pb', 'jelly']) == ['pb', 'jelly']
+" <
+function! maktaba#value#AsList(Value_or_values) abort
+  return maktaba#value#IsList(a:Value_or_values) ?
+      \ a:Value_or_values : [a:Value_or_values]
+endfunction
+
+
 ""
 " Focuses on a part of {target} specified by {foci}. That object will either be
 " returned, or set to [value] if [value] is given (in which case {target} is

diff --git a/doc/maktaba.txt b/doc/maktaba.txt
@@ -1898,6 +1898,14 @@ maktaba#value#IsCallable({value})                 *maktaba#value#IsCallable()*
 maktaba#value#IsEnum({value})                         *maktaba#value#IsEnum()*
   1 if {value} is a maktaba enum type, 0 otherwise.
 
+maktaba#value#AsList({value_or_values})               *maktaba#value#AsList()*
+  Coerces {value_or_values} into a list, wrapping any non-list value into a
+  single-item list. Examples:
+>
+    maktaba#value#AsList('lonely') == ['lonely']
+    maktaba#value#AsList(['pb', 'jelly']) == ['pb', 'jelly']
+<
+
 maktaba#value#Focus({target}, {foci}, [value])         *maktaba#value#Focus()*
   Focuses on a part of {target} specified by {foci}. That object will either
   be returned, or set to [value] if [value] is given (in which case {target}

diff --git a/vroom/value.vroom b/vroom/value.vroom
@@ -181,6 +181,19 @@ The empty funcref value is function('empty').
 
 Cute.
 
+You can also coerce an arbitrary value into a list using maktaba#value#AsList
+(wrapping non-list values into their own single-item list).
+
+  :echomsg string(maktaba#value#AsList('lonely'))
+  ~ ['lonely']
+  :echomsg string(maktaba#value#AsList({'abc': 123}))
+  ~ [{'abc': 123}]
+
+If the value is already a list, it's returned unchanged.
+
+  :echomsg string(maktaba#value#AsList(['pb', 'jelly']))
+  ~ ['pb', 'jelly']
+
 
 
 Sometimes you want to check whether a variable can be called, or whether