use typoscript variable in condition - typo3

Question

Is it possible to use variables defined in TypoScript in TypoScript conditions?
For example if I define a variable like this:
my_var = 10
Can I create a condition in typoscript that checks if my_var equals 10?
I imagine something like this:
my_var = 10
[my_var = 10]
# do something
[else]
# do something else
[end]
The reason why I need this is the lack of nested conditions. If what I'm asking for is possible, I can do something like this to overcome this limitation:
[globalVar=TSFE:id=1]
# render special layout for page 1
[else]
normal_layout = 1
[end]
[normal_layout = 1] && [globalVar=TSFE:page|layout=1]
# render normal layout 1
[end]
[normal_layout = 1] && [globalVar=TSFE:page|layout=2]
# render normal layout 2
[end]
Another usecase would be to check for the existence of a variable, for example if page was already defined. Example:
[globalVar=TSFE:id=1]
page = PAGE
page.10 = TEXT
page.10.value = hello page 1!
[end]
[!page]
page = PAGE
page.10 = TEXT
page.10.value = hello world!
[end]
I'm surprised that the docs don't answer this already :S
edit
I've tried Andreas Ottos solution, but it still does not seem to work. Here's my example code:
lib.content = TEXT
lib.content.value = this text should not get displayed
[globalVar=TSFE:id=1]
lib.content = TEXT
lib.content.value = this is page 1
[else]
normal_layout = 1
[end]
[globalVar = LIT:1 = {$normal_layout}]
lib.content = TEXT
lib.content.value = this is any other page
[end]
page = PAGE
page.10 < lib.content
In theory, this should render 'this is page 1' for page 1 and 'this is any other page' for any other page. But while page 1 gets rendered correctly, this is not the case for the other pages. They get rendered with 'this text should not get displayed'.
Any ideas? I'm using version 7.6. Is that maybe the problem?

Answer 1

EDIT: For the first UseCase:
It is possible with a TypoScript "literal". See a small hint in the doc here.
And you have to separate the constants from the logic.
So in the constants you have to write:
[globalVar=TSFE:id=1]
normal_layout = 0
[else]
normal_layout = 1
[end]
And in the setups part you can use this variable:
[globalVar = LIT:0 = {$normal_layout}]
# render special layout for page 1
[end]
[globalVar = LIT:1 = {$normal_layout}] && [globalVar=TSFE:page|layout=1]
# render normal layout 1
[end]
[globalVar = LIT:1 = {$normal_layout}] && [globalVar=TSFE:page|layout=2]
# render normal layout 2
[end]
Your second usecase is not really clear but I would recommend to use a base definition of page which is overwritten in the specific cases.