Replaces the text in the given file - FAKE F#MAKE - f#

Question

I am new to FAKE and trying to implement something in FAKE as described below :
I have a file having more than 100 lines, I want to change few lines in the code , let say I want to change 2nd line i.e. IFR.SIIC._0.12 to
IFR.SIIC._0.45
How will I do this .
Will I do this using ReplaceInFile or RegexReplaceInFileWithEncoding ?

Answer 1

There are many functions that could help you: which one you'll pick will depend on how you'd prefer to write your code. For example, ReplaceInFile wants you to supply it with a function, while RegexReplaceInFileWithEncoding wants you to give it a regular expression (in string form, not as a Regex object). Depending on what text you want to replace, one might be easier than the other. For example, you could use ReplaceInFile like so:
Target "ChangeText" (fun _ ->
"D:\Files\new\oneFile.txt" // Note *no* !! operator to change a single file
|> ReplaceInFile (fun input ->
match input with
| "IFR.SIIC._0.12" -> "IFR.SIIC._0.45"
| "another string" -> "its replacement"
| s -> s // Anything else gets returned unchanged
)
)
That would be useful if, for example, you have a set of specific strings that you want to match, in just a single file. However, there's a simpler function called ReplaceInFiles (note the plural) which allows you to replace text in multiple files at once. Also, instead of taking a function as its parameter, ReplaceInFiles takes a sequence of (old,new) pairs. This is often easier to write:
let stringsToReplace = [
("IFR.SIIC._0.12", "IFR.SIIC._0.45") ;
("another string", "its replacement")
]
Target "ChangeText" (fun _ ->
!! "D:\Files\new\*.txt"
|> ReplaceInFiles stringsToReplace
)
If you want to specify your search and replacement strings in the form a regular expression, then you'd want RegexReplaceInFileWithEncoding or RegexReplaceInFilesWithEncoding (note the plural: the former takes a single file while the latter takes multiple files). I'll just show you an example of the multiple-files version:
Target "ChangeText" (fun _ ->
!! "D:\Files\new\*.txt"
|> RegexReplaceInFilesWithEncoding #"(?<part1>\w+)\.(?<part2>\w+)\._0\.12"
#"${part1}.${part2}._0.45"
System.Text.Encoding.UTF8
)
That would allow you to change IFR.SIIC._0.12 to IFR.SIIC._0.45 and ABC.WXYZ._0.12 to ABC.WXYZ._0.45.
Which one of these you'll want to use all depends on how many files you have, and how many different replacement strings you need (and how hard it would be to write them a regex).