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Some questions about witz [message #37117]

Sun, 26 August 2012 07:46

dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Hi Mirek,

Welcome back from the holiday, I hope you enjoyed it Smile

I finally got time to play with skylark for a while and I found couple things around witz that seem a bit impractical to me...

1) If id is encountered for which there is corresponding #define, it is replaced by empty text (quoted from witz docs). Is this by design to make things simpler or is it just arbitrary decision that can be changed? I think there is many situations where you want to use the same fragment many times. For example:

<html>
<head>
<title>#TITLE</title>
</head>
<body>
<h1>#TITLE</h1>
some text
</body>
</html>

#define TITLE Skylark test

For me this code doesn't even behave as described in tutorial, the h1 element is not empty, but it renders as literal string "#TITLE".

2) On similar note, replacing unknown defines by empty string is making it hard to work with inlined css. Also, the results are somewhat inconsistent. Example:

<style type="text/css">
.style1 {background-color: #8888FF;}
.style2 {background-color: #FF8888;}
#content {position: absolute; left: 150px;}
</style>

renders as

<style type="text/css">
.style1 {background-color: #8888FF;}
.style2 {background-color: ;}
 {position: absolute; left: 150px;}
</style>

As you can see, where the define is valid "C identifier", it is replaced by empty string, otherwise it stays. This can be worked around by using external styles, but that makes debugging harder, since browser tend to heavily cache those. Also, when you want to use witz to generate the styles, this might be problem. Handling colors can worked around by using rgb(255,128,128) syntax, resulting in more writing, but working CSS. Setting style to element with given id, e.g. #content, is probably not possible at all. What about just leaving any unknown substitution in the text as is?

3) Expresions like map[key] are said to work in witz tutorial, but as far as I can tell it is not implemented yet.

4) In dot notation "value.field", it is not possible to use fields that are not valid C identifiers. As a result, you can not directly access values in variable corresponding to e.g. VectorMap<int,String>, because "map.0" makes the parser fail. I know that in this syntax it looks weird, but since the map[0] doesn't work, it is all we got. I think that the CParser would need a new method for this, something like ReadWord(), which would be used instead of ReadId() and would read all continuous non-whitespace characters, including special symbols etc.

I hope this is not too much criticism at once Smile

It just accumulated in me over the last week as I waited till you get back Very Happy

Best regards,
Honza

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Re: Some questions about witz [message #37118 is a reply to message #37117]

Sun, 26 August 2012 13:57

mirek
Messages: 13975
Registered: November 2005

Ultimate Member

Thank you, you are right at all points Smile

All should be now resolved, documentation updated.

upptst/witz is now dedicated to Witz testing...

Mirek

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Re: Some questions about witz [message #37124 is a reply to message #37118]

Mon, 27 August 2012 08:50

dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Great, thanks! Smile

That was easy, I was expecting more of a discussion Very Happy

Honza

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Re: Some questions about witz [message #37319 is a reply to message #37117]

Fri, 21 September 2012 23:34

dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Hi Mirek,

I think I found another little bug Smile

The subscript operators sometimes work wrong for maps with numeric indices. Testcase:

handler

SKYLARK(HomePage, "")
{
ValueMap m;
m.Add(1, "first");
m.Add(2, "second");

http("TEST", m)
.RenderResult("Test/index");
}

index.witz

This renders as:

TEST = { 1: first, 2: second }
TEST[0] = first
TEST[1] = second
TEST[2] = second
TEST[3] =

To fix it, it is necessary to first check for ValueMap and only after that try ValueArray in ExeBracket::Eval():

Value Compiler::ExeBracket::Eval(ExeContext& x) const
{
	Value m = value->Eval(x);
	Value q = index->Eval(x);
	if(IsValueMap(m)) {
		ValueMap map = m;
		return map[q];
	}
	if(IsNumber(q) && IsValueArray(m)) {
		ValueArray va = m;
		int i = q;
		if(i >= 0 && i < va.GetCount())
			return va[i];
	}
	return Value();	
}

With this fix it renders correctly as

TEST = { 1: first, 2: second }
TEST[0] =
TEST[1] = first
TEST[2] = second
TEST[3] =

Is this solution correct?

Best regards,
Honza

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Re: Some questions about witz [message #37323 is a reply to message #37319]

Sat, 22 September 2012 09:48

mirek
Messages: 13975
Registered: November 2005

Ultimate Member

dolik.rce wrote on Fri, 21 September 2012 17:34

Is this solution correct?

Not really. See IsValueArray/IsValueMap, they are the same because ValueArray is compatible with ValueMap (they are convertible).

But hopefully it is now fixed this way (please check):

Value Compiler::ExeBracket::Eval(ExeContext& x) const
{
	Value m = value->Eval(x);
	Value q = index->Eval(x);
	if(IsNumber(q) && m.Is<ValueArray>()) {
		ValueArray va = m;
		int i = q;
		if(i >= 0 && i < va.GetCount())
			return va[i];
	}
	if(IsValueMap(m)) {
		ValueMap map = m;
		return map[q];
	}
	return Value();	
}

Mirek

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Re: Some questions about witz [message #37326 is a reply to message #37323]

Sat, 22 September 2012 18:56

dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Yes, now it works exactly as I wanted Smile

... and more logical IMHO. The ValueMap<->ValueArray compatibility is an interesting catch, I didn't know about that till now.

Thank you,
Honza

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