CODEWITHSUNDEEP
c++
Vikram Singh
Vikram Singh

Reputation: 273

single object accessing two functions in c++

What is this piece of code doing?

SNMP_Sequence trapseq = trap.GetPDU().GetVarBindList();

As far as I know, an object can refer to only one member function at a time. What is happening here? trap.GetPDU().GetVarBindList()

Upvotes: 0

Views: 71

Answers (3)

Alok Save
Alok Save

Reputation: 206566

trap.GetPDU() returns an object and GetVarBindList() is called on that object.

trap.GetPDU().GetVarBindList()

is equivalent to:

obj.GetVarBindList()

where obj is an object returned by trap.GetPDU()

This is also known as Method Chaining.

Upvotes: 4

Puppy
Puppy

Reputation: 146968

It is perfectly legitimate to call a member function upon the result of any expression, including the access to another member, should that expression be of appropriate type.

std::vector<std::vector<std::vector<std::string>>> super_jaggy;
// insert stuff here
std::cout << super_jaggy.front().front().front().size(); // legal

Upvotes: 0

James M
James M

Reputation: 16718

It's retrieving the object (or reference) that GetPDU returns, and then calling GetVarBindList on it.

Equivalent to something like:

SomeObject &PDU = trap.GetPDU();
SNMP_Sequence trapseq = PDU.GetVarBindList();

Upvotes: 0

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