Function chaining: introduce NextIf idea to not break the chain #54150

wajihkm · 2025-01-10T11:16:48Z

wajihkm
Jan 10, 2025

Hi,

Most of the classes are using function chaining to call multiple methods on the same object sequentially, with each method returning the object itself.
While this enables a clean and readable syntax for performing a series of operations, it could be improved if the developer was able to not break the chain to do some conditional check.

Here it is why I introduce the NextIf concept.
The main idea is to inject the conditional check in the chain of the functions.
$obj->fun1()->nextIf($cond)->fun2()

Sample (Current problem):

<?php

class Builder
{
  private string $value = '';

  public function buildX(string $param)
  {
    $this->value .= $param;
    return $this;
  }

  public function buildY(string $param)
  {
    $this->value .= $param;
    return $this;
  }

  public function buildZ(string $param)
  {
    $this->value .= $param;
    return $this;
  }

  public function result(): string
  {
    return $this->value;
  }
}

$builder = new Builder();
$builder
  ->buildX()
  ->buildY();

$cond = true;
if ($cond) {
  $builder->buildZ();
}

$result = $builder->result();
echo $result;

Solution:


interface NextIf
{
    public function nextIf(bool $cond): self;
    public function nextSkipIf(bool $cond): self;
    public function readNextIf(): ?bool;
}

class Builder implements NextIf
{
    private string $value = '';

    public function buildX(string $param)
    {
        if ($this->readNextIf() === false) {
            return $this;
        }

        $this->value .= $param;
        return $this;
    }

    public function buildY(string $param)
    {
        if ($this->readNextIf() === false) {
            return $this;
        }

        $this->value .= $param;
        return $this;
    }

    public function buildZ(string $param)
    {
        if ($this->readNextIf() === false) {
            return $this;
        }

        $this->value .= $param;
        return $this;
    }

    public function result(): string
    {
        return $this->value;
    }

    //

    private ?bool $nextIf = null;
    public function nextIf(bool $cond): self
    {
        $this->nextIf = $cond;
        return $this;
    }

    public function nextSkipIf(bool $cond): self
    {
        return $this->nextIf(!$cond);
    }

    public function readNextIf(): ?bool
    {
        $next = $this->nextIf;

        $this->nextIf = null;

        return $next;
    }
}

$cond = false;
$cond2 = true;
$cond3 = true;

$builder = new Builder();
$result = $builder
    ->buildX(' Step 1 ')
    ->buildY(' Step 2 ')
    ->nextIf($cond)
    ->buildZ(' Step 3')
    ->nextSkipIf($cond2)
    ->buildX(' Step 4')
    ->nextIf($cond3)
    ->buildY(' Step 5')
    ->result();

echo $result;

// output: Step 1  Step 2  Step 5