mjhjmtu

I want to use etoolbox's toggles to achieve the following: In the preamble a toggle is created, during typesetting the document its value might change and at the end I want to write the value to the aux file to access it next time. However, setting toggles in the aux file does not seem to work, as the following MWE illustrates:

documentclassminimal
usepackageetoolbox
newtoggletesttoggle

begindocument
makeatletter
immediatewrite@auxoutnoexpandtoggletruetesttoggle
makeatother
iftoggletesttoggletruefalse
enddocument

After running this, the aux file contains

relax 
toggletrue testtoggle

as it should. However, in the document created it says "false" instead of "true". How can this be fixed?

The same problem also occurs when I use newif statements instead of toggles.

The .aux file is (usually) read in a group, so all changes that you want to propagate to the entire document need to be applied globally. In this case

immediatewrite@auxoutnoexpandglobalnoexpandtoggletruetesttoggle

should be enough so that the .aux file reads

relax 
global toggletrue testtoggle

In case it is not easily possible to append global to a command (or to switch to a global version like gdef instead of def) or in case you need to do this more often you might want to consider writing an auxiliary function for the .aux file.

documentclassarticle
usepackageetoolbox
newtoggletesttoggle

begindocument
makeatletter
immediatewrite@auxoutnoexpandglobalnoexpandtoggletruetesttoggle
makeatother
iftoggletesttoggletruefalse
enddocument