Monthly Archives: November 2021

Install Docker Engine on Ubuntu

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Reading about how to Install Docker Engine on Ubuntu. I suppose it’s about time.

-------------------
Thu Nov 11 20:38:18 [bash:5.0.17 jobs:0 error:0]
root@tact:/home/jj5
# docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete
Digest: sha256:cc15c5b292d8525effc0f89cb299f1804f3a725c8d05e158653a563f15e4f685
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/get-started/

Pivot Tables

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I think the Laravel developers don’t know what a Pivot Table is. At the time of writing:

If you need to define attributes that should be set on the pivot / intermediate table linking the models, you may use the hasAttached method. This method accepts an array of pivot table attribute names and values as its second argument

The concept they’re looking for is Association Table.
Oh, look. I just noticed this on the Wikipedia article: “pivot table (as used incorrectly in Laravel – not to be confused with the correct use of pivot table in spreadsheets)”; so this has already been discovered.

Factory specialization

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I just knocked this up to confirm my thinking was right:

<?php

class StdFeature {

}

class AppFeature extends StdFeature {

}

class FactoryBase {

  public function new_feature() : StdFeature { return new StdFeature; }

}

class Factory extends FactoryBase {

  public function new_feature() : AppFeature { return new AppFeature; }

}

$factory = new Factory();

$feature = $factory->new_feature();

assert( is_a( $feature, 'AppFeature' ) );