________________________________________________________________________

This file is part of Logtalk <https://logtalk.org/>  
Copyright 1998-2021 Paulo Moura <pmoura@logtalk.org>  
SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
________________________________________________________________________


`help`
======

This tool provides basic on-line help for Logtalk features and libraries
when running in a limited set of operating-systems. For help on the
Logtalk compiler error and warning messages, see the `tutor` tool.


API documentation
-----------------

This tool API documentation is available at:

[../../docs/library_index.html#help](../../docs/library_index.html#help)

For sample queries, please see the `SCRIPT.txt` file in the tool directory.


Loading
-------

	| ?- logtalk_load(help(loader)).


Testing
-------

To test this tool, load the `tester.lgt` file:

	| ?- logtalk_load(help(tester)).


Supported operating-systems
---------------------------

Currently, support is limited to Linux, macOS, and Windows.

On Windows, the `start` command must be available. On Linux, the `xdg-open`
command must be available. On macOS, the command `open` is used.

This tool relies on the library portable operating-system access abstraction.

Usage
-----

After loading the tool, use the query `help::help` to get started.

Known issues
------------

On macOS, the `open` command used to open documentation URLs drops the anchors,
thus preventing navigating to the specified position on the documentation page.

ECLiPSe defines a `help` prefix operator that forces wrapping this atom between
parenthesis when sending messages to the tool. E.g. use `(help)::help` instead
of `help::help`.
