"Change All Occurrences" doesn't work well

[ojwb]

Cut and paste this into owlet:

F.F=F TOF S.F:READF$:F%=F*LENF$:P.F$,F%:N.
D.F

Then right click on one of the F variables in the code and select "Change All Occurrences", then type X. The program now looks like this:

X.X=X TOF S.X:READF$:X%=X*LENF$:P.X$,X%:N.
D.X

I'd expect it only to change uses of the variable F, but it's also changed:

• F. is FOR abbreviated
• F$ and F% are also matched when not preceded by a keyword
• F in D.F is really a string constant not the variable F in this program (though if it were read into a numeric variable it would be a the variable F so this one more forgivable)

It's also failed to match variable F when preceded by a keyword (TOF). I guess it assumes C-like tokenisation rules.

I can see this feature would be handy for golfing code if it actually worked, but if it can't be persuaded to understand BBC BASIC tokenisation rules then perhaps it would be better turned off in owlet. When I first tried it on a real example it looked like it had worked, but actually it had missed a use of the variable, and so broke the code.

[ojwb]

Oh, or is this actually just a textual search and replace feature?

The way it's presented made me expect it to be a more IDE-like refactoring tool, but I just noticed it seems to present some icons at the top right, one of which is "Use Regular Expression" - that makes me think it's actually just textual search and replace (though I've so far failed to work out how to actually search for a regular expression using it...)

[ojwb]

https://devblogs.microsoft.com/python/bringing-the-power-of-the-monaco-editor-to-nteract/ says:

The right-click menu exposes the Change All Occurrences feature, which allows you to easily rename all instances of a variable within a cell at once.

So Microsoft think it does what I expected it to, not what it actually does in owlet. Perhaps it needs some language-specific support to work properly? Even for a language where keywords can be matched by word-boundary rules you need to account for the same word but in a string, which means it needs to understand string quoting rules.

[mattgodbolt]

It definitely needs language-specific support. Right now Monaco falls back to text replacement.

[ojwb]

Right now Monaco falls back to text replacement.

Ah yes, it even replaces inside string literals.