daisy-consortium/pipeline-modules-common — pull request #17 by josteinaj (2013-05-14 15:39:44+00:00)
Title: processor independent logging steps: px:message/px:error/px:assert

All steps takes a "message" option and nine optional `param[1-9]` options.
`$1, $2, ..., $9` in the message value will be replaced with the values
in their corresponding param option. For instance:

```xml

```

The above code will output `[INFO] The current XProc processor is: XML Calabash`.

The `px:message` step has a `severity` option that can be either
WARN, INFO or DEBUG. The default is INFO. There is no ERROR level as
that is what px:error is meant for.

The `px:error` step has the `code`, `code-prefix` and `code-namespace` options.
These are equivalent to the ones used for the standard `p:error` step, except
that the namespace has to be specified explicitly when a prefix is used; it
cannot be inferred from the calling pipeline. For instance:

```xml

```

(As with `p:error`, a un-prefixed code with no namespace can be used as well)

The `px:assert` step has the `test` option which must be `true` or `false`.
It also takes the optional options `error-code`, `error-code-prefix`
and `error-code-namespace` which are provided to `px:error` if the value of
`test` is `false`. If no error code is provided, a warning is displayed using
`px:message` instead. For instance:

```xml

```

`px:message` and `px:assert` (unless an error is thrown) works like a `p:identity`
step in that they output the same as they get in.

The steps are used by importing `http://www.daisy.org/pipeline/modules/common-utils/logging-library.xpl`

These are the step signatures:

```xml

```

```xml

```

```xml

```