Modules and uses

As a program grows, it makes sense to split it into smaller, reusable files. In NeoObjectPascal this is done with the uses clause, which loads both internal libraries and file-based modules that you write yourself.

The uses clause

The uses clause appears at the beginning of the program, before any declaration. It lists the modules to load, separated by commas, and ends with ;:

uses internal.math, internal.string;

begin
    WriteLn("Máximo: ", max(10, 20));
    WriteLn("Maiúsculas: ", toUpperCase("neo"));
end.

Saída

 Máximo: 20 Maiúsculas: NEO 

After the uses, all functions from the modules become available as if they had been declared in your own file.

Internal libraries vs. file-based modules

There are two kinds of modules, distinguished by their prefix:

Form	Origin	Example
internal.<name>	Libraries bundled inside the interpreter itself	uses internal.datetime;
<folder>.<module>	.npas file relative to your program	uses utils.matematica;

The internal. prefix is reserved: the runtime recognizes it and loads the library from inside the JAR. Any other path is treated as a file in your project.

Creating a file-based module

A module is simply a .npas file with declarations of functions, procedures, or variables. For example, create matematica.npas:

// matematica.npas
function somar(a: Integer, b: Integer): Integer
begin
    return a + b;
end;

function subtrair(a: Integer, b: Integer): Integer
begin
    return a - b;
end;

And use it in the main program, in the same directory:

// programa.npas
uses matematica;

begin
    WriteLn(somar(10, 5));
    WriteLn(subtrair(10, 5));
end.

Saída

 15 5 

The interpreter looks for matematica.npas starting from the directory of the main file.

The parameter separator is the comma

When declaring typed parameters, separate them with a comma: function somar(a: Integer, b: Integer). Do not use a semicolon between parameters.

Hierarchical modules

You can organize modules into subfolders using a dot as the path separator. uses utils.matematica; loads the file utils/matematica.npas, relative to the main program:

projeto/
├── programa.npas
└── utils/
    └── matematica.npas

// programa.npas
uses utils.matematica;

begin
    WriteLn(somar(2, 3));
end.

Saída

 5 

Loading multiple modules

A single uses clause can mix internal libraries and your own modules, all separated by commas:

uses internal.math, internal.string, utils.matematica;

begin
    WriteLn(square(4));              // de internal.math
    WriteLn(quote("olá"));          // de internal.string
    WriteLn(somar(1, 1));           // do seu módulo utils.matematica
end.

Saída

 16 "olá" 2 

Best practices

• Group related functions in the same module (for example, all text functions in a texto.npas).
• Prefer many small, cohesive files over a single giant file.
• Use subfolders (utils., dominio.) to organize modules by area of the system.
• There is only one uses clause per program: list all modules in it.

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Next, get to know each of the Internal Libraries in detail.