{"title":"Complex values in Smalltalk","authors":"Thomas J. Schrader, Christian Haider","doi":"10.1145/1735935.1735957","DOIUrl":"https://doi.org/10.1145/1735935.1735957","url":null,"abstract":"Distinguishing between stateful objects and Values has long been recognized as fruitful. Values are universal context free abstractions that prevent side-effects and allow for a functional programming style. Though object-oriented programming languages provide simple Values like Integer and String, more complex Values are usually not supported. We show how to model complex structures as Values in Smalltalk, which allows for a simple and versatile implementation. The resulting Smalltalk systems are simple, clear and easily testable.","PeriodicalId":393791,"journal":{"name":"International Workshop on Smalltalk Technologies","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114621068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evolving a reflective language: lessons learned from implementing traits","authors":"Stéphane Ducasse, M. Denker, Adrian Lienhard","doi":"10.1145/1735935.1735949","DOIUrl":"https://doi.org/10.1145/1735935.1735949","url":null,"abstract":"Traits are method groups that can be used to compose classes. They do not have a runtime existence and are conceptually folded into the classes that use them. Traits have been implemented in different languages. While implementing them in Smalltalk, our first reflex was to take advantage of the fact that traits are not run-time entities: we optimized the implementation for space and hence shared methods between traits and classes. However, by doing so we broke the introspective API of Smalltalk.\u0000 This paper illustrates a more general problem seen in all reflective systems: the implementation serves both as a model for execution and as the model that is exposed to the programmer. There is a conflict of interests between the information necessary for execution and the information the programmer is interested in. In addition, as soon as the implementation is exposed via reflection, we are not free to optimize. As the complete implementation is visible reflectively, there is no way to hide the optimizations.\u0000 Few papers report errors and this is one of them. We report our experience facing the initial API mismatch, which has a significant impact on the system because the language is reflective (i.e., written in itself and causally connected). We present the new introspective API we put in place.","PeriodicalId":393791,"journal":{"name":"International Workshop on Smalltalk Technologies","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121552007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}