Posts Tagged Override
MacVim, NerdTree, Janus Annoyances
I’ve decided to use Vim for a few weeks at least and am enjoying it. There are plenty of posts on using Vim as a Ruby IDE and switching from your IDE of choice. Most of the TextMate to Vim posts seem to recommend Janus and for good reason.
Janus adds a number of plugins and settings to Macvim including NerdTree. NerdTree displays a project drawer in a window which is in a vertical split, normally alomgside your working buffer. The first problem is that if you close your working buffer with :bd or :bw, the NerdTree window will fill the MacVim tab, to cycle to the next or previous buffer then entails resizing splits which is not what I want.
Janus solves this with a function in .vimrc:
This function closes the MacVim tab (i.e. Cmd + W) if there is only one tab and it contains 2 windows, one of them with the NerdTree buffer. Unfortunately this doesn’t consider buffers that are not currently displayed. If I want to close MacVim or the MacVim current tab, I’ll use Cmd + Q or W, when I delete a buffer I want the window to display the next buffer.
To disable the Janus function add an override to .vimrc.local:
It’s better to make changes in .vimrc.local and .gvimrc.local as Janus can be updated to the latest version without losing your customisations.
Luckily there is a script on the vim wiki that keeps the window open when deleting a buffer. It can be amended to ignore the NerdTree buffer, if I want to close NerdTree I will use the key mapped to toggle it:
I would like to map :bd to :Kwbd but it seems it can’t be done (I’d be happy to be proved wrong here) so have mapped Ctrl + Shift + B in .vimrc.local:
Entity Classes, IDs and Equality
Posted by John in Methodology on April 22, 2010
I want my entity classes to rely on their ID when checking equality, the ID is populated from the repository when I retrieve an object and automatically generated when I save a new entity.
This poses the problem of how I compare two entities before they have been saved while working with them in my domain, or, when I have ‘newed’ them up myself for unit testing. The answer is to use a transient ID.
Normally an Entity Base class might look like this:
public abstract class EntityBase : IEquatable<EntityBase> {
public virtual int Id { get; protected set; }
public override bool Equals(object other) {
return Equals(other as EntityBase);
}
public override int GetHashCode() {
return Id;
}
public virtual bool Equals(EntityBase other) {
if (other == null) return false;
return other.Id == Id && other.GetType() == GetType();
}
}
If two new objects are created from a derived class then object1.Equals(object2) will be true as Id will be 0 for both objects. To avoid this I need to check if an object has not yet been saved:
private bool IsTransient {
get { return Id == 0; }
}
And just check for referential equality if this is the case:
public virtual bool Equals(EntityBase other) {
if (other == null) return false;
if (IsTransient) return ReferenceEquals(this, other);
return other.Id == Id && other.GetType() == GetType();
}
GetHashCode() needs to be overridden to reflect this:
public override int GetHashCode() {
if (IsTransient) return base.GetHashCode();
return Id;
}
The full code for EntityBase is:
public abstract class EntityBase : IEquatable<EntityBase> {
public virtual int Id { get; protected set; }
private bool IsTransient {
get { return Id == 0; }
}
public override bool Equals(object other) {
return Equals(other as EntityBase);
}
public override int GetHashCode() {
if (IsTransient) return base.GetHashCode();
return Id;
}
public virtual bool Equals(EntityBase other) {
if (other == null) return false;
if (IsTransient) return ReferenceEquals(this, other);
return other.Id == Id && other.GetType() == GetType();
}
}