Add artist to filename only if artist != albumartist

[bernd-wechner]

I thought this pattern might do the trick:

$if(%discnumber%, %discnumber% - ,)$num(%track%,2) - %title%$if(NOT %artist% EQUAL %albumartist%,  - %artist%,)

But alas when artist and albumartist are equal this is appending "- %artist" albeit without a space in front of the "-".

So clearly I have some syntax to learn here ;-). But I've read the docs and haven't progressed. So I hope an issue is the right way to go.

[bernd-wechner]

Well, well, well ... drilled into it and the reason is that the if function is a little dumb ;-). As in it check's for the truth condition with:

puddletag/puddlestuff/functions.py

Line 103 in 09500dc

def check_truth(text):

which does not do any logical operator parsing. It's a simple Python truthy test. So another strategy is required or a smarter check_truth.

[bernd-wechner]

And voila an alternative approach that does work:

$if(%discnumber%, %discnumber% - ,)$num(%track%,2) - %title%$if($replace(%artist%, %albumartist%,),\ - %artist%,)

Key things to observe and document better:

1. The $if function's first argument is false only if it's an empty string of the string '0' it handles no fancy boolean logic.
2. If you put quotes around %tagname% then it is not expanded, you get a literal "%tagname"
   • I would suggest that the parser would be easily made better by respecting a shell like difference with single quotes functioning this way but double quotes supporting replacement of %tagname% with it's value.
   • I'm happy to loook into fixing it thusly if a PR is welcome and time permits.
3. The backslash is honoured to insert a literal space, though oddly seems not needed for the trailing space in $if(%discnumber%, %discnumber% - ,) but needed in the leading space of %$if($replace(%artist%, %albumartist%,),\ - %artist%,)
   • I'd recommend consistency here.
   • Am again happy to consider fixing it to be consistent if a PR is welcome and time permits.

For now I am content that I have a pattern that does what I want.