argstart

Argstart is a term used in computer programming to denote the position in a list or array of command-line arguments where non-option arguments begin after option-like tokens have been processed. It is not a standardized keyword or feature of any single language but appears in discussions and code in various command-line parsing utilities.

Origin and usage:

The concept arises when a parser separates flags and options (typically starting with a dash) from positional arguments (such as files or input values). Argstart marks the first index in the argument vector that is considered a positional argument. Variations exist in naming: some projects use arg_start, first_positional, or first_arg. The exact semantics depend on the specific parser, but the common idea is the boundary between options and positional arguments.

Examples:

Pseudocode: tokens = input_args; i = 0; while i < len(tokens) and tokens[i].startswith('-'): i += 1; argstart = i

In environments that support an explicit end-of-options marker (for example --), argstart may be the index after the marker if present; otherwise it equals the index after option processing.

Relation to libraries:

Many command-line parsing libraries expose a mechanism that effectively returns or stores the argstart value, indicating where positional arguments begin after option processing, or provide equivalent access via parsing state.

Limitations:

Argstart is not a formal language feature. Its exact meaning and naming vary by project, so documentation should define its semantics in that context.