Fixing a Target Order based on the requested target?

[Yannick Koehler]

Hello,

 I have a project where I can generated 5 targets.  All of them are
PHONY targets.  Those targets can all be generated individually except
one which require at least 1 of the other to be done before itself.

Example:

.PHONY: a b c d e
a:
 @echo "Target $@ is Done"
b:
 @echo "Target $@ is Done"
c:
 @echo "Target $@ is Done"
d:
 @echo "Target $@ is Done"
e:
 @echo "Target $@ is Done"

I can do

make a
make b
make c
make d

but I cannot do

make e

without having built at least one of a,b,c or d... but not necessarily
all of them.  Considering that it takes 1 hour to build a,b,c and d...
I'd like to tell GNU make that if I someone do "make a e", "make b e"
or "make a b e" it's fine, but "make e" alone is bad...

I have not found a way to do this...

--
Yannick Koehler
email: address@hidden
blog:   http://yannick.koehler.name