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Quotes in constants - tell me I'm wrong …
Posted: Sat Dec 31, 2022 1:02 pm
by Fjord
Hi,
I'm parsing HTML and I've got several strings that act as patterns, like
of course this could be a constant; actually, it
should be a constant:
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constant laCleFinTable = "</table"
But I have also
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put "<table class=""e&"table table2""e&" id=""e&"partants_table_" into laCleDebutTable
and this
can't be a constant because it embeds quotes. I couldn't find a way to embed a quote within a string without using the & operator. And constants can't embed any operator.
Did I get it correctly? or is there a way to write a string constant containing quotes?
BTW, some languages allow you to write constants like:
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constant laCleDebutTable = "<table class=\"table table2\" id=\"partants_table_" -- see example above
constant ten = 2*5 -- kind of silly, of course
constant pi = arcCos(-1) -- not as silly as it seems
a constant being just something that is evaluated only once, probably by the compiler, or at the beginning of the handler or sub.
Re: Quotes in constants - tell me I'm wrong …
Posted: Sun Jan 01, 2023 5:26 am
by mwieder
Yes, it's unfortunately a LiveCode limitation.
There's a long-standing bug report/enhancement request to allow single quotes, which would help alleviate this problem.
Constants will soon (fingers crossed) more flexible in what they allow as expressions.
For now I create fake constants
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local kFakeConstant
put "<table class=""e&"table table2""e&" id=""e&"partants_table_" into kFakeConstant
# and then use the fake constant afterwards as if it were a real constant.
put kFakeConstant into laCleDebutTable
Another solution is to use custom properties of a stack or control
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set the fakeConstant of this stack to "<table class=""e&"table table2""e&" id=""e&"partants_table_"
put the fakeConstant of this stack into laCleDebutTable
Re: Quotes in constants - tell me I'm wrong …
Posted: Sun Jan 01, 2023 11:34 am
by Fjord
… I was wondering if I missed something ; thanks for confirming I did not
Happy new year to all!!
Re: Quotes in constants - tell me I'm wrong …
Posted: Mon Jan 02, 2023 2:24 pm
by stam
Fjord wrote: ↑Sat Dec 31, 2022 1:02 pm
and this
can't be a constant because it embeds quotes.
It's nothing to do with
quotes specifically - it's that you can
only have string literals (and no function such as something that returns a double quote) in a constant declaration.
Longstanding limitation and if I'm not mistaken one LC said they would change with upcoming releases to allow functions/operators in constant declarations... Something I'd expect to be changed quite soon...
S.
Re: Quotes in constants - tell me I'm wrong …
Posted: Thu Jan 05, 2023 9:18 pm
by mwieder
I see constant expression evaluation should be in the next release
https://quality.livecode.com/show_bug.cgi?id=12802