Using composite_formatter.safe_format with multiline text?

[kiwidude]

I'm moving an email conversation to here.

I am enhancing the Generate Cover plugin to support template driven expressions from a text input field. I thought it would be nice if I changed the input to be a multiline QTextEdit, thereby allowing the user to do multiline expressions like:

Genre: {tags}\n
Published: {pubdate}

However the problem I have is that composite_formatter.safe_format() strips newline characters out. Now if I substitute in something else like <br/> it will work, but then it will blow up if you try to use a multiline complex {} expression.

Any suggestions? I need something that template formatter won't strip out that I can split on afterwards, but that won't cause multi-line formulas to blow up...

Or do we just tell users not to do multi-line formulas?

[chaley]

Can't you treat each line as a separate template?

[kiwidude]

I don't think so? I can't split before I call the template formatter, because I might be splitting in a formula. I was trying to avoid complicating my UI (and all the code related to drawing) by having multiple UI controls. Or were you thinking of something else?

[chaley]

I was assuming that the values between the { } characters never contain newlines. I don't see why they should.

If this is true, then the following should work.

lines = text.split('\n')
result = []
for l in lines:
    result.append(composite_formatter.safe_format(l, mi, 'XXX', mi))
val = '\n'.join(result)

This code gives you back the multiline text, with template fields inserted.

Am I missing something?

[kiwidude]

Well, I was looking at your examples of what people "could" do in templates with functions and program mode. Your examples on the help page show multi-line templates inside the {}.

Now if you say those are "not likely" scenarios or something I needn't bother supporting then fair enough...

[chaley]

General program mode templates do not go between {} characters. They must begin with the word 'program:' and the program goes until the end of the string. The concept of a multiline template goes away, because the entire string is one template. It makes little sense to me for someone to use a general program mode template in the situation you are describing. If they *really* need something of that complexity to generate a field value, then they can use a composite column or build a python template function.

Template program mode expressions can in theory be multiline, but in practice they never are. I think it is safe not to support them.

One thing that my suggestion does not cover is fields that contain explicit newlines, where these newlines are significant. Non-multiple text fields come to mind. These normally use HTML, so I am not convinced this is a problem. Is it?

BTW: I have no particular problem with adding a parameter to safe_formatter not to collapse white space. I just want to be sure it is needed before I do it. If I do this, then you could pass the entire string in one go. The downside is that there would be no white space processing, so templates like
"abc {series} def" would evaluate to "abc def" (two spaces) if there is no series. Perhaps this is OK.

[kiwidude]

If you are happy multiple template expressions aren't frequently needed, that is good enough for me. I just wanted to make sure I wasn't putting an unreasonable restriction in. So don't bother about the parameter, thanks.