latex_macros: don't evaluate anything on startup

[jhpalmieri]

Right now, sage.misc.latex_macros evaluates lots of things on startup. The attached patch modifies this: after the patch, the list of LaTeX macros is only computed when asked for.

There needs to be a corresponding change in sagenb: pull request

Depends on #13717

CC: @vbraun

Component: misc

Keywords: latex macros

Author: John Palmieri

Reviewer: Volker Braun

Merged: sage-5.7.beta0

Issue created by migration from https://trac.sagemath.org/ticket/13504

[jhpalmieri]

comment:1

Attachment: trac_13504-latex-macros.patch.gz

[jhpalmieri]

Description changed:

--- 
+++ 
@@ -1 +1,4 @@
 Right now, `sage.misc.latex_macros` evaluates lots of things on startup. The attached patch modifies this: after the patch, the list of LaTeX macros is only computed when asked for.
+
+There needs to be a corresponding change in sagenb: [pull request](https://github.com/sagemath/sagenb/pull/96)
+

[vbraun]

comment:2

Maybe I'm missing something, but can't we avoid the bracket bonanza LatexCall()(x) with a lazy import? As in http://www.sagemath.org/doc/reference/sage/misc/lazy_import.html

• don't import sage.misc.latex anywhere on startup
• define an instance latex = LatexCall() in sage.misc.latex
• lazy import it from sage.misc.all, say

[jhpalmieri]

comment:3

latex has more uses than just latex(x), which is part of the problem: latex.blackboard_bold(...) uses sage_latex_macros. If we define latex = LatexCall(), then we lose

latex.add_macro                             latex.extra_macros
latex.add_package_to_preamble_if_available  latex.extra_preamble
latex.add_to_mathjax_avoid_list             latex.has_file
latex.add_to_preamble                       latex.mathjax_avoid_list
latex.blackboard_bold                       latex.matrix_delimiters
latex.check_file                            latex.pdflatex
latex.engine                                latex.vector_delimiters

With the patch, we should only have to do LatexCall()(x) a few times, in latex_macros.py; elsewhere, we can just use latex(x).

[vbraun]

comment:4

Patch doesn't apply on sage-5.4.beta1. For starters there is no mention of mathjax in doc/common/conf.py. Are you missing a dependency?

[vbraun]

Reviewer: Volker Braun

[vbraun]

comment:5

Just noticed that I accidentally applied it to sage-5.3, not 5.4.beta1. Does indeed work fine on the newest version. Patch looks good to me.

Maybe I can interest you in reviewing #13361 which improves the measurement of the startup time?