Messing With Your Heads

This is just something fun in the compiler I discovered. It will make the newbs flee 😢 and the veterans will simply whack me with a rolled up newspaper and sternly say "NO! BAD!" 😠

Compile this:

!define `War"="What is it good for?"$\n!define: "Result` Nothing!
!error `Result = ${War"="What is it good for?"$\n!define: "Result}` 

And you will see this in the compiler output:

Processing script file: "C:\NOBAD.nsi"

!define: "War"="What is it good for?"

!define: "Result"="Nothing!"

!error: Result = Nothing!

What dose this mean?
Basically you can make a define be just about ANY VALUE as long as it is is defined in one line and is wrapped in string delimiter.

Example:

!define `${__DATE__}1234567890-=~!@#$%^&*()_+qwertyuiop[]\{}|asdfghjkl:";'zxcvbnm,./<>? $\n$\t$\r` 21
!define /math "The Meaning of Life the Universe, Everything!" ${${__DATE__}1234567890-=~!@#$%^&*()_+qwertyuiop[]\{}|asdfghjkl:";'zxcvbnm,./<>? $\n$\t$\r} * 2
!error `Result = ${The Meaning of Life the Universe, Everything!}` 

Results:

!define: "6/23/20101234567890-=~!@#$%^&*()_+qwertyuiop[]\{}|asdfghjkl:";'zxcvbnm,./<>? 

	

"="21"

!define: "The Meaning of Life the Universe, Everything!"="42"

!error: Result = 42

🧟 Messes with your head doesn't it? 😕

Originally Posted by Zinthose View Post

🧟 Messes with your head doesn't it? 😕

Err... No it doesn't? It's doing exactly what it should. Of course you can make a define be just about any value. That's the whole point. It's just the preprocessor doing a straight text-replace.

I know it's working as intended.. I'm just impressed how well it's doing it 🙂

Actually, according to the manual the following:

$\r $\n $\t $$

Are listed under variables, but as I found out the hardway before, they are predefines.

Like:
StrCmp $R2 $\t 0 +3
ends up being
StrCmp $R2 0 +3

It does get people confused

Originally Posted by gringoloco023 View Post

$\r $\n $\t $$
..., they are predefines.

If that was 100% true, the following would work.

!echo One$\r$\n!echo Two 

However, It fails with an error when compiling...

!echo expects 1 parameters, got 2.

Odly though this will compile...

!define Test `One`$\r$\n!echo Two
!echo ${Test} 

but the second !echo is lost in Limbo somewhere.

I gave this some quick additional test and strangely enough it only seems to happen for $\t !

StrCpy $R2 $\t

Error: StrCpy expects 2-4 parameters, got 1.

While
StrCpy $R2 '$\t'
Compiles fine !

You can also do some interesting things with comment blocks...

!define Result1 /* Inline comments don't effect anything */ "I am assigned to Result1!"
!define Result2 /* That is...
    ...until you add a line break */ "Errors here!" 

!define: "Result1"="I am assigned to Result1!"

!define: "Result2"=""

Invalid command: Errors here!

My personal favorite is:

!define a blah

DetailPrint ${a}

DetailPrint $${a}

StrCpy $0 $$

DetailPrint $0{a}

besides all the fun,

I really consider the way how NSIS handles $\t, to be a BUG.
And maybe consider relocating $\t,$\r,$\n,$$, from constant variables to pre-defines, in the NSIS manual !

regards

Originally Posted by gringoloco023 View Post

I really consider the way how NSIS handles $\t, to be a BUG.
And maybe consider relocating $\t,$\r,$\n,$$, from constant variables to pre-defines, in the NSIS manual !

I agree, the $\t dose appear to be a bug. However, I do not agree that they should be converted to pre-defines as it would cause a few problems.

Predefines are part of the precompiler. Thus, the compiler would have to deal with multi-line string values / statements as the $\n and $\r meta sequences are replaced. At the moment it can't. (Although I wish it it did at times)

StrCpy $0 "Hello$\nWorld!" 

Would become...

StrCpy $0 "Hello
World!" 

See the problem?

It would be awesome though to have a few new predefines to play with so I could create some more complex precompiler macros.

• ${\n}
• ${\r}
• ${\t}