Data References

This page is still under construction!

When it comes to memory management, is important to understand what is data references and dereferencing data before knowing how to use it.

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In diverse cases, it's usefull, better for performance or just innavoidable to handle some process with the data source instead of a copy of it. To solve this problem, all systems allows two ways of moving data around:

Sending Data By Value

means that the data being assigned is not the source, but a copy of it. Let's take a example:

const source = 10
const copy1 = source
const copy2 = source

both copy1 and copy2 have the same value stored in source: 10. It doesnt mean that copy1 and copy2 are refering source.

from Std.Console import

const source = 10
const copy1 = source
const copy2 = source

writeln("original source = \{source}")
writeln("original copy1 = \{copy1}")
writeln("original copy2 = \{copy2}")

# Modifying...
copy2 = 20
copy1 = 5

writeln("source = \{source}")
writeln("copy1 = \{copy1}")
writeln("copy2 = \{copy2}")

Console Output

original source = 10
original copy1 = 10
original copy2 = 10
source = 10
copy1 = 5
copy2 = 20

With this code is possible to see that source, copy1 and copy2 has independent values, though receiving it from the same field reference. This is explained though the fact that the computer makes a copy of the value in source instead of derreferencing the field itself. This way, any modifications on data received by value will not be reflected in the original data source.

Sending Data By Reference

means that the data being assigned is a reference to the source. Follow the example:

const source = 10
const copy1 = source
const ref1 = &source
const ref2 = &source

The unary operator & returns the reference of the field instead of it value. This means that ref1 and ref2 now points to source.

from Std.Console import

const source = 10
const copy1 = source
const ref1 = &source
const ref2 = &source

writeln("original source = \{source}")
writeln("original copy1 = \{copy1}")
writeln("original ref1 = \{ref1}")
writeln("original ref2 = \{ref2}")

# Modifying...
ref1 = 5
ref2 = 7

writeln("source = \{source}")
writeln("copy1 = \{copy1}")
writeln("ref1 = \{ref1}")
writeln("ref2 = \{ref2}")

Console Output

original source = 10
original copy1 = 10
original ref1 = 10
original ref2 = 10
source = 7
copy1 = 10
ref1 = 7
ref2 = 7

This example shows that assiging a value to ref2 resulted in both source and ref2 being changed to this value too. In reality, only the value of source is changing and it content is being reflected by ref1 and ref2.