Thoughts on agile software development
FreshMarker as a Template Engine supports a whole range of data types for its model values. This data type are usually a mapping of the corresponding Java types such as String, Boolean, Long, Beans, Records, List and Maps. In addition, FreshMarker has the data type Range, which describes intervals with a lower and an optional upper limit.
In the previous article on operator overloading, the implementation for the numerical addition and multiplication operators was presented. In this article, some other operators will be provided with this feature and some details will be discussed that should be taken into account when operator overloading.
Operator overloading is a programming technique in which an existing operator is extended or adapted to user-defined data types. This makes it possible to design user-defined classes in such a way that they behave syntactically like built-in data types and facilitates intuitive and readable use of these types using the familiar operators. This article presents the integration of operator overloading in FreshMarker.
Sometimes a new feature also needs to be a bit of fun. When updating the FreshMarker Grammar, I noticed that the operators lt, gt, gte and lte were still present. These are variants of the usual <, >, <= and >= operators and are reminiscent of the opcodes of a long-forgotten era when assembler languages still roamed the steppes of programming. Since FreshMarker was given its Unicode capabilities by CongoCC, the question arose as to why not allow ≠ and other operator characters in the template.
Some FreshMarker additions are too small to present individually in a blog post. For this reason, there will now be a brief overview of the latest changes to the library from time to time. Up to the current version 1.6.0, the following changes have been made in recent weeks.
It will come as no surprise that FreshMarker, like all other template engines, must take precautions against template injection. Template injection is a security vulnerability that occurs when an application handles templates insecurely. Templates are prefabricated files or strings with placeholders that are replaced by data from users or other sources. Similar to FreeMarker, FreshMarker also has an escape mechanism that detects special characters in the interpolations using a harmless variant. If the standard mechanism is not enough, OWASP can help out.
In the first article on FreshMarker performance, some of the template engine’s speed problems were addressed. The benchmark showed a tripling of the speed for these adjustments. In this article, the use of Reflections will be removed, which is certainly also of interest outside of a template engine.
FreshMarker started as an academic project. The main aim was to show how a template engine can be created. At some point, however, the question arose as to how fast the template engine actually is. To be honest, it has been slow so far. But first things first.
FreshMarker is quite a small library, about 475 KB in size. Therefore there is always room to make a few small additions. One of these is the display of numbers and loop variables with Roman numerals.
At the end of the summer vacation, here is the last post on the topic of Partial Template Reduction for the time being. The basic algorithm was presented in the first two articles. In this article, the missing variable support is added.