Skip to content

Format: accept a named pattern or a blank as the argument, e.g. Format[t_h] := ... #1997

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
rocky merged 1 commit into from
Oct 16, 2026
Merged

Format: accept a named pattern or a blank as the argument, e.g. Format[t_h] := ... #1997

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 9 additions & 5 deletions mathics/eval/assignments/assignment.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -471,11 +471,15 @@ def eval_assign_format(
]
lhs = lhs.elements[0]
lhs_unwrapped = unwrap_expression(lhs)
lhs_unwrapped = (
lhs_unwrapped.get_head()
if not isinstance(lhs_unwrapped, Symbol)
else lhs_unwrapped
)
# For a named pattern or a blank, as in Format[t_h] or Format[_h],
# keep the pattern: the tag is h, which is found inside it below.
# Otherwise, the tag is the head, as in Format[h[x_]].
if not (
isinstance(lhs_unwrapped, Symbol)
or lhs_unwrapped.has_form(SymbolPattern, 2)
or lhs_unwrapped.get_head() in BLANK_PATTERN_HEADS
):
lhs_unwrapped = lhs_unwrapped.get_head()
target_symbol_names = collect_lhs_names_and_upset_dont_allow_custom(
target_symbol_names, upset, op_name, lhs, lhs_unwrapped, evaluation
)
Expand Down
16 changes: 16 additions & 0 deletions test/builtin/assignments/test_assignment.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -178,6 +178,22 @@ def test_assign_list():
'"{2, a}"',
"store the conditional rule for T...",
),
# Named patterns and blanks as the argument of Format
(
'ClearAll[A,G]; Format[A_G]:="g" /; Length[A] > 1; {G[1,2], G[1]}//ToString',
'"{g, G[1]}"',
"Format[A_G] is stored for G, not for Pattern",
),
(
'ClearAll[G]; Format[_G]:="g"; G[1]//ToString',
'"g"',
"Format[_G] is stored for G",
),
(
'ClearAll[t,G]; Format[t:G[__]]:="g"; G[1]//ToString',
'"g"',
"Format[t:G[__]] is stored for G",
),
# Upvalues
(
"ClearAll[F,A,Y,x]; A=T; F[A[x_],Y[x_]]^:=x^2; ClearAll[A,F,Y]; F[T[2],Y[2]]",
Expand Down
Loading