RE: [htmltmpl] TMPL_IF truth vs definition

[Chris D. <Chr...@Ma...>]

On Friday, June 21, 2002 3:14 UTC, Tugrul Galatali wrote:

> [...] I had gotten into the habit of using TMPL_IF in the sense of if a
variable is defined instead of if it is true. Now 99% of the time this just
happens to work, as most defined things are also considered to be true. But
that 1% needs to be dealt with.

> I realize I could do this with H::T::Expr, but I don't want to go that far
(and it would require changing a lot of templates ;). And I could start
evaluating the defined condition in the code and exporting booleans, but
that triggers the valid warning in the documentation about that.

> The question I have is how to proceed:
> 1) Add a flag to switch TMPL_IF to the alternate behaviour (if defined vs
if true)
> 2) Add another tag TMPL_IFDEF or similar.

I don't really see why you can't take the pain and amend your CGI scripts.
What documentation warnings are you referring to, that advise against this
course of action? (I can see one warning against matching TMPL_IF to perl if
statements, but that doesn't seem to apply.)

Consider the H::T snippet,
	<TMPL_IF NAME="my_bool">...</TMPL_IF>

In your CGI, instead of writing simply,
	{ my_bool => $x }

you would write something like this,
	{ my_bool => defined $x }

Here's a corresponding (trivial) truth table, from which you should be able
to take the appropriate expressions:

$x		defined $x	defined $x && $x	defined $x && 1
---------------	---------------	---------------	---------------
undef		undef		""		""
0		1		0		1
1		1		1		1
2		1		2		1

Chris
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