SCR101: undefined-name

Name is not defined anywhere the script can see

Code	SCR101
Name	undefined-name
Category	Scripts (SCR)
Default severity	error
Enabled by default	yes
Fix available	no
ign-lint equivalent	none

What it does

Reports names that are bound nowhere the code can see them: not in the function, not in an enclosing function, not at module level, not a Jython builtin and not one of the names Ignition provides to the script.

Ignition provides, without import (verified on an 8.3 gateway): system, fpmi (legacy alias of system), sys, __builtins__, the generated function's own name, and every top-level package or module of the project's script library (core for core/util/code.py), including those of child projects when the script belongs to an inheritable project. Library modules also have __name__ (and __package__ once an import has run), but not __file__.

The scoping rules are Python 2.7's: list comprehension variables leak into the enclosing scope, generator expressions do not; names bound in a class body are not visible to its methods.

The rule stays silent where it cannot be sure: in scopes with from x import * or unqualified exec; in a module that writes its own namespace (exec code in globals(), also in d, globals(), globals()['x'] = ..., globals().update(...), setattr(sys.modules[__name__], ...), sys.modules[__name__].x = ...) or the builtins (__builtins__['x'] = ..., setattr(__builtin__, ...), __builtin__.x = ...); in a function that runs exec code in locals() (or in vars(), in globals(), locals()), whose names Jython looks up at run time; inside a try whose handlers catch NameError, in projects whose parent project is not part of the linted tree (its library is unknown), and for the 7.x prefixes project., shared. and app. (reported by SCR206).

Not checked at all: a .py file outside any project (no project.json in its directory or a parent directory, such as a loose file linted on its own) and the tag scripts of gateway resources. Any name they do not bind could be a top-level package of the script library they run with, which iglint does not know there, so no name is reported, not only names that look like packages. Lint the file as part of its project to check it.

Why is this bad?

The script raises NameError when it reaches the name. In a Perspective event that means the action silently does nothing but log an error; in a transform the binding gets an error quality.

Example

def runAction(self, event):
    rows = system.db.runNamedQuery("Lines/All")
    for row in rows:
        lineName = row["name"]
    self.view.custom.last = linename

Use instead:

def runAction(self, event):
    rows = system.db.runNamedQuery("Lines/All")
    for row in rows:
        lineName = row["name"]
    self.view.custom.last = lineName

pylint

Corresponds to E0602 undefined-variable. Differences, all because pylint assumes CPython 3: pylint reports system, the project's library packages and the header parameters of Perspective scripts (iglint knows them), and reports list comprehension variables used after the comprehension (they leak in Jython 2.7). pylint does not report __file__ in library modules, which Ignition does not define.

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Generated from the rule metadata by iglint generate-docs; iglint rule SCR101 prints the same page in the terminal. Source: docs/rules/SCR101.md.