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How do I use push_output?

The subroutine push_output(type[,data]) takes two arguments: the type, which is always required, and the data, which is needed for certain types of output. Table 3 lists the different types which you can push onto the output stack.

Table 3: Types for push_output

Type

'handle'

Data

a filehandle

Description

Send all output to the supplied filehandle.

Type

'file'

Data

a filename

Description

Open the supplied file for writing, erasing its current contents (if any), and send all output to it.

Type

'append'

Data

a filename

Description

Open the supplied file for writing and append all output to its current contents.

Type

'pipe'

Data

a shell command

Description

Pipe all output to the supplied shell command.

Type

'string'

Data

a string [optional]

Description

Append all output to the supplied string, which will be returned by pop_output.

Type

'nul'

Data

[none]

Description

Ignore all output.

Because the output is stack-based, you do not lose the previous output destination when you push a new one. This is especially convenient for dealing with data in tree-structures, like SGML data -- for example, you can capture the contents of sub-elements as strings, ignore certain types of elements, and split the output from one SGML parse into a series of sub-files. Here are some examples:

push_output('string');                  # append output to an empty string
push_output('file','/tmp/foo');         # send output to this file
push_output('pipe','mail webmaster');   # mail output to 'webmaster' (!!)
push_output('nul');                     # just ignore all output

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