ZYBNET

GitHub Pages is a free hosting service that can effectively be used for static content. For example this site is entirelty made up of HTML files in the master branch of the repository raffaelesgarro.github.io. Only two things are needed:

• a CNAME record in the DNS
• a CNAME file to instruct the Pages virtual host

I just bootstrapped a droplet on DigitalOcean and deployed a Java app developed with Spring boot. I quickly tested it by logging into and clicking here and there, and then moved on configuring Nginx.

And suddenly my app disappeared!

$ curl -I localhost:8080
Connection refused

See this JSFiddle

<div>
    <div>cell lorem ipsum</div>
</div>

<div>
    <div>cell lorem ipsum</div>
    <div>cell lorem ipsum</div>
</div>

<div>
    <div>cell lorem ipsum</div>
    <div>cell</div>
    <div>cell lorem ipsum</div>
</div>

<div>
    <div>cell lorem ipsum</div>
    <div>cell</div>
    <div>cell</div>
    <div>c</div>
</div>

<div>
    <div>cell lorem ipsum</div>
    <div>cell</div>
    <div>c</div>
    <div>cell</div>
    <div>c</div>
</div>

<div>
    <div>cell lorem ipsum</div>
    <div>c</div>
    <div>c</div>
    <div>cell</div>
    <div>cell</div>
    <div>c</div>
</div>

Take this load of questions:

• Why can I put an Integer in a List<Number> but can’t assign a List<Integer> to a List<Number>?
• Why can I put any Number in a List<? super Number> but can’t do the same with a List<? extends Number>?
• Why doesn’t List<? extends Number> extends List<? super Number>?

Derby doesn’t support the MS proprietary UPDATE FROM SELECT, nor does it support the SQL standard MERGE so I had to write the following script to update a table from values retrieved from a select. It uses a temporary table and a subquery in the SET clause. I had to add an index to the temporary table to speed up things:

The method createTemplate() inside SimpleTemplateEngine builds a template from a String, and then make(bindings) replaces placeholders with values from the hash.

As advertised in the documentation, placeholders are given in JSP or GString style, so the problem is: how do we escape JSP and GString delimiters? That is, how can we insert a plain $foo or a literal <%=bar%> without the engine complaining about missing keys when binding?

Explain the following snippet found in a Rails controller:

def index
  @posts = Post.all

  respond_to do |format|
    format.html  # index.html.erb
    format.json  { render :json => @posts }
  end
end

Useful link to Ruby procs, blocks and lambdas

In Scala you can write

trait ConstrainedTrait { self: ParentType =>
  // code here
}

Mail thread here

Explain the following Groovy code:

[ compileJava, compileTestJava ]*.options*.encoding = 'UTF-8'

Explanation here

I had to write a method which, given an Enum class, returned the set of values. First signature attempt:

public Set<Enum<?>> getValuesForEnum(Class<Enum<?>> klass);

Unfortunately this doesn’t work. When you try to invoke this method you got the error:

getValuesForEnum() can't be applied to "name.of.the.Enum"