Singleton: Difference between revisions
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I am a singleton
</pre>
=={{header|M2000 Interpreter}}==
<syntaxhighlight lang="m2000 interpreter">
Module CheckSingleton {
\\ singleton
\\ pointers and static groups are the same object because
\\ each one has a pointer to same state (a tuple)
\\ but from outside we do the miracle to have a static group to act as a pointer
\\ We need a lambda function to hold the pointer to Singleton as closure
Global One=lambda M=pointer() (aValue=0)-> {
If M is type null then
\\ one time happen
Group Singleton {
Type:One
Private:
state=(aValue,)
Public:
module Add (x) {
.state+=x
}
Set {Drop}
Value {
=.state#val(0)
}
}
M->group(Singleton)
end if
\\ return M which is a pointer
=M
}
K=One(100)
Print Eval(K)=100
M=One()
Print Eval(M)=100
Print K is M = true
Print K is type One = true
K=>add 500
Print eval(K)=600
\\ copy K to Z (no pointer to Z, Z is named group)
Z=Group(K)
Print eval(z)=600, z=600
Z.add 1000
Print Z=1600, Eval(M)=1600, Eval(K)=1600
\\ push a copy of Z, but state is pointer so we get a copy of a pointer
Push Group(Z)
Read beta
Beta.add 1000
Print Z=2600, Eval(M)=2600, Eval(K)=2600
\\ convert pointer to group (a copy of group)
group delta=One()
delta.add 1000
Print Z=3600, beta=3600, delta=3600, Eval(M)=3600, Eval(K)=3600
\\ M and K are pointers to groups
M=>add 400
Print Z=4000, beta=4000, delta=4000, Eval(M)=4000, Eval(K)=4000
}
CheckSingleton
</syntaxhighlight>
=={{header|Lasso}}==
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