For this week’s blog we are going to create a simple calculator using Legato. Legato offers a wide variety of math functions that we can use to program the calculator. Before we get started coding, let’s think about the parts of the script we will need. First there will need to be a user interface. In our case, a dialog works perfectly. Secondly, we need to have a way to store operands, and a floating point number is good choice here. If we use only an integer the user cannot do decimal math. Finally, we will need to have operation processing. For this we will use Legato’s math functions. To begin I am going to set up the basics of the dialog, and we can add the processing together.

This week we released version 4.22b of the GoFiler line of products, and with the release came new Legato functions to control Internet Explorer through OLE. Note that in future releases of Legato we will be adding further OLE functionality. The concepts used in this blog can be applied to any other OLE automation project.

This week we are going to discuss hashing. Simply put, a hashing function takes arbitrary sized data and maps it to fixed size in a deterministic manner. Therefore, when given the same input, the same result is generated. Ideally, a hash function would be 1-1, as in for every input a unique output is given. This is also known as an injective function. In reality, though, that’s not possible since the amount of data being input can be many times larger than the output. So instead hashing algorithms aim to be uniform, which is to say they use the entire output space equally. This means that the chances of two inputs generating the same hash are lower given the size of the output hash.

During my last blog I discussed using background scripts. This week I will elaborate more on synchronizing background scripts and their data. If you haven’t read the previous blog don’t worry, you will be able to follow along. However, this blog does require at least a basic understanding of threading. The first part used a single background thread to track user activity within the application. A background thread is used to allow the user to continue to work in parallel to our script. Another way to use background scripts is to take a task and process it in parallel. Our script this week is an example of this.