Command-line interface

You can execute arbitrary scripts with instrumentation enabled using the pyc command-line tool (installed as both pyc and pyccolo). For example, to run some script bar.py under the optional-chaining example tracer:

# bar.py
bar = None
# prints `None` since bar?.foo coalesces to `None`
print(bar?.foo)

$ pyc bar.py -t pyccolo.examples.optional_chaining.ScriptOptionalChainer

You can also run bar as a module (indeed, pyc does this internally when given a file):

$ pyc -m bar -t pyccolo.examples.optional_chaining.ScriptOptionalChainer

The -t value is a fully-qualified reference to a tracer class. Note that we use ScriptOptionalChainer rather than the bare OptionalChainer: because pyc runs your file through Pyccolo’s import machinery, the tracer must opt that file in by overriding should_instrument_file() (which ScriptOptionalChainer does, and OptionalChainer does not — see Tracing real programs).

You can specify multiple tracer classes after -t; in case you were not already aware, Pyccolo is composable!

Options

Pyccolo command line tool.

usage: pyc [-h] [-m MODULE] -t TRACER [TRACER ...] [script]

Positional Arguments

script: Script to run with instrumentation.

Named Arguments

-m, --module: The module to run, if script not specified.
-t, --tracer: Tracers to use for instrumentation.