TiXmlHandle¶
from panda3d.core import TiXmlHandle
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class
TiXmlHandle
¶ A TiXmlHandle is a class that wraps a node pointer with null checks; this is an incredibly useful thing. Note that TiXmlHandle is not part of the TinyXml DOM structure. It is a separate utility class.
Take an example:
<Document> <Element attributeA = "valueA"> <Child attributeB = "value1" /> <Child attributeB = "value2" /> </Element> <Document>
Assuming you want the value of “attributeB” in the 2nd “Child” element, it’s very easy to write a lot of code that looks like:
TiXmlElement* root = document.FirstChildElement( "Document" ); if ( root ) { TiXmlElement* element = root->FirstChildElement( "Element" ); if ( element ) { TiXmlElement* child = element->FirstChildElement( "Child" ); if ( child ) { TiXmlElement* child2 = child->NextSiblingElement( "Child" ); if ( child2 ) { // Finally do something useful.
And that doesn’t even cover “else” cases. TiXmlHandle addresses the verbosity of such code. A TiXmlHandle checks for null pointers so it is perfectly safe and correct to use:
TiXmlHandle docHandle( &document ); TiXmlElement* child2 = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).Child( "Child", 1 ).ToElement(); if ( child2 ) { // do something useful
Which is MUCH more concise and useful.
It is also safe to copy handles - internally they are nothing more than node pointers.
TiXmlHandle handleCopy = handle;
What they should not be used for is iteration:
int i=0; while ( true ) { TiXmlElement* child = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).Child( "Child", i ).ToElement(); if ( !child ) break; // do something ++i; }
It seems reasonable, but it is in fact two embedded while loops. The Child method is a linear walk to find the element, so this code would iterate much more than it needs to. Instead, prefer:
TiXmlElement* child = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).FirstChild( "Child" ).ToElement(); for( child; child; child=child->NextSiblingElement() ) { // do something }
Inheritance diagram
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Child
(value: str, index: int) → TiXmlHandle¶ Return a handle to the “index” child with the given name. The first child is 0, the second 1, etc.
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Child
(index: int) → TiXmlHandle Return a handle to the “index” child. The first child is 0, the second 1, etc.
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Child
(_value: str, index: int) → TiXmlHandle
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ChildElement
(value: str, index: int) → TiXmlHandle¶ Return a handle to the “index” child element with the given name. The first child element is 0, the second 1, etc. Note that only
TiXmlElements
are indexed: other types are not counted.
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ChildElement
(index: int) → TiXmlHandle Return a handle to the “index” child element. The first child element is 0, the second 1, etc. Note that only
TiXmlElements
are indexed: other types are not counted.
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ChildElement
(_value: str, index: int) → TiXmlHandle
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Element
() → TiXmlElement¶ Deprecated: use
ToElement()
.Return the handle as a
TiXmlElement
. This may return null.
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FirstChild
() → TiXmlHandle¶ /// Return a handle to the first child node.
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FirstChild
(value: str) → TiXmlHandle /// Return a handle to the first child node with the given name.
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FirstChild
(_value: str) → TiXmlHandle
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FirstChildElement
() → TiXmlHandle¶ /// Return a handle to the first child element.
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FirstChildElement
(value: str) → TiXmlHandle /// Return a handle to the first child element with the given name.
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FirstChildElement
(_value: str) → TiXmlHandle
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Node
() → TiXmlNode¶ Deprecated: use
ToNode()
.Return the handle as a
TiXmlNode
. This may return null.
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Text
() → TiXmlText¶ Deprecated: use
ToText()
Return the handle as a
TiXmlText
. This may return null.
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ToElement
() → TiXmlElement¶ Return the handle as a
TiXmlElement
. This may return null.
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ToUnknown
() → TiXmlUnknown¶ Return the handle as a
TiXmlUnknown
. This may return null.
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Unknown
() → TiXmlUnknown¶ Deprecated: use
ToUnknown()
Return the handle as a
TiXmlUnknown
. This may return null.
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__init__
(ref: TiXmlHandle)¶ /// Copy constructor
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__init__
(_node: TiXmlNode) /// Create a handle from any node (at any depth of the tree.) This can be a null pointer.
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assign
(ref: TiXmlHandle) → TiXmlHandle¶
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