Contract
Return type	wob
Parameter key	Default value	Type
a_string	req	string
returns	"first"	type.<one_of "first" "last" "all"/>
Parameter kind	Default value	Type
Other unkeyed arguments	req with ekind of expression	wob

Water Contract
<method pattern.replace_string_segments a_string=req=string returns ="first"=<type.one_of "first" "last" "all"/> _other_unkeyed=req=wob=ekind.expression="_body"/>

See also: get_string_segments

Uses a pattern an its subpatterns to match string segments in an input string that are to be replaced.

a wob
Parameter key Default value Type
_subject false
A pattern to find in the input string. The pattern will usually have sub-patterns, some of which are named.

a wob
Parameter key Default value Type
a_string req string
The input string to find matches in.

a wob
Parameter key Default value Type
returns "first" type.<one_of "first" "last" "all"/>
How much of the input string to match. See get_string_segment for a description of "first", "last" and "all".

Below we have the input string of "frontazzzmiddlebzzzend". We have specified a pattern that can find "azzz" and "bzzz". For each of those patterns, the code in the content of the replace_string_segments call, ie "pre".<join prefix.<to_uppercase/> "post"/> is executed in an environment with the local variable prefix having the value of "a" for the first match of the pattern and "b" for the second match of the pattern. So for the first match, the code returns "preApost" and for the seond match it returns "preBpost". These computed strings replace the substring that was matched, so the output string, "frontpreApostmiddlepreBpostend" is the same as the input string except that "azzz" has been replaced with "preApost" and "bzzz" has been replaced with "preBpost".

<pattern pattern.<named "prefix" pattern.<one_of "a" "b"/>/>  "zzz"/>.
    <replace_string_segments "frontazzzmiddlebzzzend" returns="all">
      "pre".<join prefix.<to_uppercase/> "post"/>
  </>

"frontpreApostmiddlepreBpostend"

replace_string_segments is a powerful string transformation tool. Note that the named patterns to match and make into local variables must be immediate sub-patterns of the _subject pattern.