Lints

Below are all of the lints currently supported in duck.

Tag	Default Level	Explanation
accessor_alternative	LintLevel::Warn	GML offers accessors as an alternative to many common functions which are preferable for their readability and brevity.
and_preference	LintLevel::Allow	GML supports both and and && to refer to logical "and". Consistent use of one over the other yields cleaner code.
anonymous_constructor	LintLevel::Allow	Constructors should be reserved for larger, higher scoped types.
bool_equality	LintLevel::Allow	Comparing a bool with a bool literal is more verbose than neccesary.
casing_rules	LintLevel::Allow	Like any programming language, GML contains many different symbols that all can be styled in different ways. Picking consistent rules for each type creates a cleaner and more consistent codebase.
collapsable_if	LintLevel::Warn	If statements that contain nothing more than another if statement can be collapsed into a single statement.
condition_wrapper	LintLevel::Allow	Parenthesis surrounding certain statement expressions are optional in GML, resulting in differing opinions on whether or not to use them. You can select either option via the config.
deprecated	LintLevel::Warn	Deprecated features are liable to be removed at any time and should be avoided.
draw_sprite	LintLevel::Allow	Projects that implement their own rendering backend may wish to be restrictive around when and where the draw_sprite functions are called.
draw_text	LintLevel::Allow	Projects that implement their own UI frameworks / localization may wish to be restrictive around when and where the draw_text functions are called.
english_flavor_violation	LintLevel::Allow	GML has many duplicated function names for the sake of supporting both British and American spelling. For consistency, codebases should stick to one.
exit	LintLevel::Allow	return can always be used in place of exit, which provides more consistency across your codebase.
global	LintLevel::Allow	While useful at times, global variables reduce saftey since they can be accessed or mutated anywhere, and provide no guarentee that they've already been initiailized.
invalid_assignment	LintLevel::Deny	Certain assignment patterns are valid in gml but are undefined behavior and have no valid use cases.
invalid_comparison	LintLevel::Deny	Certain types allow comparison checks in gml but are undefined behavior and have no valid use cases.
invalid_equality	LintLevel::Deny	Certain types allow equality checks in gml but are undefined behavior and have no valid use cases.
missing_case_member	LintLevel::Warn	Switch statements matching over an enum typically want to cover all possible cases if they do not implement a default case.
missing_default_case	LintLevel::Allow	Switch statements are often used to express all possible outcomes of a limited data set, but by not implementing a default case, no code will run to handle any alternate or unexpected values.
mod_preference	LintLevel::Allow	GML supports both mod and % to perform modulo division. Consistent use of one over the other yields cleaner code.
multi_var_declaration	LintLevel::Allow	While GML allows you to create multiple local variables at once, it can often lead to confusing syntax that would read better with each variable seperated.
non_constant_default_parameter	LintLevel::Warn	Expressive default parameters are not supported in most languages due to their instability and tendency to hide important logic execution from the caller.
non_simplified_expression	LintLevel::Warn	Operating on two constant numbers can be reduced for brevity.
not_preference	LintLevel::Allow	GML supports both not and ! to refer to unary "not". Consistent use of one over the other yields cleaner code.
or_preference	LintLevel::Allow	GML supports both or and `
room_goto	LintLevel::Allow	Projects that implement their own frameworks for room management may wish to be restrictive around when and where the room_goto functions are called.
show_debug_message	LintLevel::Allow	Projects often implement their own logging framework and wish to avoid unwrapped prints to the console.
single_equals_comparison	LintLevel::Warn	The single-equals token can be used for both assignments and equalities in gml. This is atypical of most languages, and can lead to inconsistancies or bugs in projects.
single_switch_case	LintLevel::Warn	Switch statements that only match on a single element can be reduced to an if statement.
suspicious_constant_usage	LintLevel::Deny	Using a constant outside of equalities and direct assignments is likely unintended or misunderstood code.
switch_without_case	LintLevel::Warn	A switch statement is unncessary if it contains now cases.
todo	LintLevel::Allow	Todo markers are useful for work-in-progress code, but often are not intended to be permanently in place.
too_many_arguments	LintLevel::Warn	Functions with lots of parameters quickly become confusing and indicate a need for structural change.
try_catch	LintLevel::Allow	GML's try/catch will collect all errors as opposed to the precise ones wanted, allowing them to accidently catch errors that should not be surpressed.
unassigned_constructor	LintLevel::Warn	Invoking a constructor function without saving the new struct is often a mistake. If the constructor is saving a refernce of itself within its own declaration, this should still be given a wrapper function so that the behavior is not hidden. Avoiding this as an intentional pattern allows this lint to better alert you to mistakes.
unnecessary_grouping	LintLevel::Warn	Parenthesis around an expression that do not change how the logic is executed are redundant and can be removed.
unused_local_variable	LintLevel::Warn	Unused local variables are at best clutter and at worst the source of hard-to-spot bug.
unused_parameter	LintLevel::Warn	Parameters that are never referenced are often a canary towards a larger bug.
useless_function	LintLevel::Deny	Anonymous functions that are not assigned to a variable can never be referenced.
var_prefix_violation	LintLevel::Allow	It is common practice in GML to prefix local variables (longer than one charcter) with an underscore as it helps to visually distinguish them from instance (or global) variables. You can select either option via the config.
with_loop	LintLevel::Allow	The with loop allows your code's context to suddenly change, both making it more difficult to read (as a given line of code is no longer promised to be executing in the scope expected from the file), but also making it more difficult to track down all of the places an object is modified.