Warning
THIS MODULE DOES NOT HAVE STABLE PUBLIC API
Simple interface class for plainbox commands.
Command objects like this are consumed by PlainBoxTool subclasses to implement hierarchical command system. The API supports arbitrary many sub commands in arbitrary nesting arrangement.
Enable automatic pager.
This invokes autopager() which wraps execution in a pager program so that long output is not a problem to read. Do not call this in interactive commands.
Base class for implementing commands like ‘plainbox’.
The tools support a variety of sub-commands, logging and debugging support. If argcomplete module is available and used properly in the shell then advanced tab-completion is also available.
There are three methods to implement for a basic tool. Those are:
This class has some complex control flow to support important and interesting use cases. There are some concerns to people that subclass this in order to implement their own command line tools.
The first concern is that input is parsed with two parsers, the early parser and the full parser. The early parser quickly checks for a fraction of supported arguments and uses that data to initialize environment before construction of a full parser is possible. The full parser sees the reminder of the input and does not re-parse things that where already handled.
The second concern is that this command natively supports the concept of a config object and a provider object. This may not be desired by all users but it is the current state as of this writing. This means that by the time eary init is done we have a known provider and config objects that can be used to instantiate command objects in add_subcommands(). This API might change when full multi-provider is available but details are not known yet.
Add top-level subcommands to the argument parser.
This can be overriden by subclasses to use a different set of top-level subcommands.
Create a parser that captures some of the early data we need to be able to have a real parser and initialize the rest.
Do very early initialization. This is where we initalize stuff even without seeing a shred of command line data or anything else.
Do some final initialization just before the command gets dispatched. This is empty here but maybe useful for subclasses.
Enable automatic pager
Parameters: | pager_list – List of pager programs to try. |
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Returns: | Nothing immedaitely if auto-pagerification cannot be turned on. This is true when running on windows or when sys.stdout is not a tty. |
This function executes the following steps:
- A pager is selected
- A pipe is created
- The current process forks
- The parent uses execlp() and becomes the pager
- The child/python carries on the execution of python code.
- The parent/pager stdin is connected to the childs stdout.
- The child/python stderr is connected to parent/pager stdin only when sys.stderr is connected to a tty
Note
Pager selection is influenced by the pager environment variabe. if set it will be prepended to the pager_list. This makes the expected behavior of allowing users to customize their environment work okay.
Warning
This function must not be used for interactive commands. Doing so will prevent users from feeding any input to plainbox as all input will be “stolen” by the pager process.
Find the first executable from name_list in PATH
Parameters: | name_list – List of names of executable programs to look for, in the order of preference. Only basenames should be passed here (not absolute pathnames) |
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Returns: | Tuple (name, pathname), if the executable can be found |
Raises: | LookupError if none of the names in name_list are executable programs in PATH |
plainbox.impl.color – ANSI color codes
plainbox.impl.commands.analyze – analyze sub-command
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