...

Does anyone know the syntax to use with dtml-if when i want to do something like this:

<dtml-if <dtml-var w>==1>

do stuff </dtml-if> ?

This means, well, nothing. It's syntactically invalid. DTML is not a macro language, but an interpreted one, and the use of DTML inside a DTML tag is at best confusing and at worst a syntax error, and in no case is such a tag evaluated. The contents of a dtml-if can be either a name (without quotes) or a python statement (inside quotes, perhaps preceded by 'expr='.)

In this case, you are asking dtml-if about the truth value of an object named '<dtml-var w>==1', which is not a valid name. Or, at least, since I haven't tried, it shouldn't be.

How is that different from

<dtml-if expr="w == 1"> ...

This is asking about the truth value of the Python expression 'w==1', which will be true iff the contents of the first thing in the DTML namespace stack (the request, parameters, properties, acquisition, dtml loops, defines, et al) with the name of 'w' is equal within the Python definition to the integer 1.

or possibly

<dtml-if expr="`w` == 1"> ...

This is asking about the truth value of the Python expression " 'w'==1 ", which means "the character 'w' is equal to the integer 1." This will never be true, since 'w' is not 1. --jcc -- "Code generators follow the 80/20 rule. They solve most of the problems, but not all of the problems. There are always features and edge cases that will need hand-coding. Even if code generation could build 100 percent of the application, there will still be an endless supply of boring meetings about feature design." (http://www.devx.com/java/editorial/15511)

What's confusing about this is that single and double quotes have the same meaning in Python... but this is not so in DTML. Not really. When you use a DTML tag like: <dtml-if "some expression"> or <dtml-var "some expression"> The "some expression" that's in double quotes is a Python expression. A Python expression is a bit of Python code that evaluates to a value. It can be simple or complex. The important thing is that it returns a value. The double quotes are not part of the expression, they merely show where the expression begins and ends. Single quotes will not work for this purpose. Single quotes *will* work if you need quote marks *within* an expression, eg: <dtml-if "my_var == 'w'"> This tests if my_var is equal to the string 'w'. If you wanted to see if my_var is equal to the value of a variable called w, you'd say: <dtml-if "my_var == w"> HTH, Dylan On Thu, 2003-09-04 at 18:08, J Cameron Cooper wrote:

...

...

Does anyone know the syntax to use with dtml-if when i want to do something like this:

<dtml-if <dtml-var w>==1>

do stuff </dtml-if> ?

This means, well, nothing. It's syntactically invalid. DTML is not a macro language, but an interpreted one, and the use of DTML inside a DTML tag is at best confusing and at worst a syntax error, and in no case is such a tag evaluated. The contents of a dtml-if can be either a name (without quotes) or a python statement (inside quotes, perhaps preceded by 'expr='.)

In this case, you are asking dtml-if about the truth value of an object named '<dtml-var w>==1', which is not a valid name. Or, at least, since I haven't tried, it shouldn't be.

...

How is that different from

<dtml-if expr="w == 1"> ...

This is asking about the truth value of the Python expression 'w==1', which will be true iff the contents of the first thing in the DTML namespace stack (the request, parameters, properties, acquisition, dtml loops, defines, et al) with the name of 'w' is equal within the Python definition to the integer 1.

...

or possibly

<dtml-if expr="`w` == 1"> ...

This is asking about the truth value of the Python expression " 'w'==1 ", which means "the character 'w' is equal to the integer 1." This will never be true, since 'w' is not 1.

--jcc

On Fri, Sep 05, 2003 at 06:52:14PM +0100, garry saddington wrote:

<dtml-if w> does what it should do but what you suggest does not work nor do any of the other combinations i have tried. I can demostrate that w=1 by displaying <dtml-var w>.

ah, but do you know whether it's 1 or "1"? If you want to treat them as equivalent, convert w to an integer. <dtml-if "int(_.getitem(w))==1"> ... -- Paul Winkler http://www.slinkp.com Look! Up in the sky! It's LUDICROUS SPUTNIK FROM PLANET POOTOOT! (random hero from isometric.spaceninja.com)

On Friday 05 September 2003 19:21, Dylan Reinhardt wrote:

On Fri, 2003-09-05 at 10:52, garry saddington wrote:

...

<dtml-if w> does what it should do

If "what it should do" means "testing the existence *and* truth of w".

If w is *any* non-False value such as 1, 2, 'hello world', or ['a','b','c'] this test will evaluate True. If w is 0, [], None, or doesn't exist, it will evaluate False. If those results are what you want, cool.

...

but what you suggest does not work nor do any of the other combinations i have tried. I can demostrate that w=1 by displaying <dtml-var w>.

Or maybe what you've demonstrated is that w is equal to '1', which is going to render the same on-screen but is not the same data. If w is a variable you're grabbing from a form, that's the case almost for certain.

You're far better off writing your tests for the *exact* condition you're testing, rather than using a broad existence/truth test and assuming the rest. If the test "w==1" does not return True, then w is not equal to 1. Maybe it's equal to something that looks like 1, but this is not the same thing.

HTH,

Dylan Thanks for all your help, it is great to feel un-isolated! I have inspected the Request object and the 1 is indeed a '1' so now it works. best regards garry