user-defined-patterns (KPT*)¶

Pattern rules

This rule is enabled by default.

What it does¶

Checks every source file against regular expressions (Rust regex syntax) defined in your project configuration, line by line. Each pattern has its own code and is addressable in select, ignore, per-file-ignores and # noqa.

Why is this bad?¶

Some conventions are specific to a project (no bare print(), no breakpoint() left behind, no unticketed TODO). A pattern rule enforces them without writing a plugin.

Example¶

print("hello")   # KPT001, with the pattern below

Use instead:

logger.info("hello")

Defining patterns¶

[[tool.konform.lint.user-defined-patterns.rules]]
id      = "KPT001"
message = "Use the project logger instead of bare print()."
pattern = '^\s*print\s*\('
files   = ["src/**/*.py"]
level   = "warning"

Patterns are loaded from the first available source:

Inline [[tool.konform.lint.user-defined-patterns.rules]] in the config file.
rules_file = "path" in [tool.konform.lint.user-defined-patterns].
konform_patterns.toml, auto-discovered next to the config file.
konform_patterns.yaml (legacy fallback).

A standalone file uses plain [[rules]] tables.

Pattern entry fields¶

Field	Required	Description
`id`	yes	Code shown in output and used for `# noqa`
`message`	yes	Human-readable description
`pattern`	yes	Regex, or a list of regexes (any match fires)
`files`	no	Glob filter; omitted means every file
`level`	no	`"error"` or `"warning"`; inherits the table's `level`
`help`	no	Guidance text shown with the violation
`multiline`	no	Match against the whole file instead of line by line
`replacement`	no	Replacement string (`$1`, `$2`, ... captures); makes the pattern fixable
`sub_rules`	no	Refinements overriding `message`/`help`; the first match wins

Sub-rules¶

Sub-rules refine the message and help for more specific matches. The first sub-rule whose pattern(s) match the already-flagged line wins.

[[rules]]
id      = "KPT901"
message = "os.environ found, discouraged in test code."
pattern = 'os\.environ'
sub_rules = [
{
pattern = ['os\.environ\.get\(', 'os\.environ\['],
message = "os.environ special_key access detected.",
help    = "Use the 'shared_fixture' fixture instead.",
},
]

With [[rules.sub_rules]] tables, each sub-rule belongs to the most recently declared [[rules]] entry.

Fix behavior¶

A pattern with a replacement is fixable; patterns without one are report-only.

Options¶

Configured in [tool.konform.lint.user-defined-patterns].

Option	Type	Default	Description
`level`	`"warning" \\| "error"`	`"warning"`	Default severity for patterns that don't set their own.
`rules_file`	`str`	unset	Load patterns from this file instead of auto-discovery.
`rules`	`array of tables`	`[]`	Inline pattern entries.

Suppression¶

x = 1  # noqa: KPT001
x = 1  # noqa: KPT  (every KPT* rule)