Tutorial Get started with OpenSCAD. Issue #347 is variable assignments in local blocks. However, I think that converting OpenSCAD into an imperative language is way too disruptive, and that reformulating assignments as definitions is the best way forward if we want to preserve the existing character of the language and maintain backwards compatibility. This permits recursive and mutually recursive local definitions. See the first pinned post here for instructions on subscribing to the mailing list. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. I think the idiomatic version is the simpler: I have seen people use the more complicated version but I can't understand why? Earlier in the thread, talking about the incomprehensible semantics of assignment statements, Mike Meyer said:this is the #1 thing aboutOpenScad that caused me to tag it as "yet another language that shouldnever have been written.". Unlike most free software for creating 3D models (such as the famous application Blender), OpenSCAD focuses on the CAD aspects rather than the artistic aspects of 3D modeling. This works. Sent from the OpenSCAD mailing list archive at Nabble.com. OpenSCAD permits a parent source file to override a definition inherited from an included source file. When I run this code: difference() { c = 5; cube(c); cube(c/2); } OpenSCAD says: Parser error in line 2: syntax error ERROR: Compilation failed! dev snapshots will follow. Flag SavageRodent - in reply to JustinSDK It doesn't really matter which, one you pick - TCL, Perl, Python, Ruby, Lua, Io, GUILE, some other, Scheme, or even something really strange like Ocaml or Haskell or R -, any of them would be a major improvement on the non-CAD part of, If you can't pick one of them, pick a bunch of them. Marius's OEP3 document is suggesting that we consider making such a language revision. I won't attempt to fully specify the scope rules in this post; that's for the future. This introduces 'sequential' local definitions, and deprecates 'assign'. Worked for me. So far so good. This behavior is due to the need to supply variable input on the command line, via the use of -D variable=value option. This killed the Forum. OpenSCAD calculates the value of variables at compile-time, not run-time. OpenSCAD is a 2D / 3D and solid modeling program which is based on a Functional programming language used to create models that are previewed on the screen, and rendered into 3D mesh which allows the model to be exported in a variety of 2D/3D file formats. please note that in OpenSCAD variables are not like ordinary programming variables as they are evaluated at compile time not run time. I want to extend this syntax to allow local recursive function definitions in all of the same contexts. And I also show that this proposal is future proof, because it can be organically extended to a richer language without breaking backward compatibility. The warning message for the above code could be: Duplicate definition of 'x'. Then it is backwards compatible and if you want to pass a function you simply have to make sure you don't have a variable with the same name. Yuck. Test cases (Peter Falke has submitted a bunch of test cases for the first case; see mailing list) Assignment over variables in anonymous blocks: union () { sphere (); { a = 3; cube (3); } } Consider the following program, which is already legal: n = 42; module m () { function f () = n; echo (f ()); m = n + 1; n = 5; echo (f ()); echo (m); } m (); This results in plana viable business strategy by: a. conducting relevant market research; b. accurately assessing resource needs; f. executea business strategy by: a. creating design briefs and prototypes that effectively communicate a design concept; b. communicating a confident, polished, convincing pitch in an oral presentation, accompanied by visual media; (OpenSCAD has the paradigm of functional programming to some aspects.) Then anything assigned to them has to be looked up as a function and any use of them is unambiguous. Thank you Doug, once again a great analysis. As we know, OpenSCAD can only assign variables in file scopes and module scopes, not anywhere else. Nabble removed Mailing-list integration from the Forum. In Scheme, there are 3 variants of 'let', which I will illustrate using OpenSCAD style syntax. By using this trick, we avoid introducing different syntactic constructs for 'sequential let' vs 'recursive let'. It is free software and available for Linux/UNIX, MS Windows and macOS. Variables can now be assigned in any local scope, effectively deprecating the assign () module: for (i= [0:2]) { j = i*2; . } CalculiX was developed by engineers from MTU Aero Engines, Munich, Germany, to assist them in designing machinery such as jet turbines. No thanks, I often use variables and functions with the same name. For this reason, I think we will eventually promote functions to first class values, and introduce a syntax for anonymous functions (lambda expressions). I want to use this feature so badly, but if thinigiverse isn't going to incorporate the build, I'll make a lot of shitty code on the internet. The C-style = is called a "destructive update operator" and reads "set .. to" (as in set myvar to 7). This is now an ARCHIVE. At the end of the include I pop the old file name and line. For the new version, pick one of the extensible embeddable, interpreters, write an extension module for the lovely OpenSCAD CAD, primitives, then embed the interpreter (or these days, links to the, shared library for it) into OpenSCAD. When I run experiments, I see mysterious behaviour that makes no sense, but since I can't find a mental model that works, I have no way of knowing if I'm seeing a bug or if it is working as designed. value is 42 because local 'b' not in scope. No warning message is issued, but a warning should be issued. (I put them in braces in the tableau). 504), Hashgraph: The sustainable alternative to blockchain, Mobile app infrastructure being decommissioned, Can't get OpenScad $Special variables to work "Correctly". OpenSCAD's math functions use the C++ 'double' type, inside Value.h/Value.cc, A good resource for the specifics of the C library math functions, . Chapter 2: Scaling the model and first steps for parameterizing models. The conditional assignment of variables is a way to instruct OpenSCAD to assign different values to variables depending on whether some condition is true or false. What I understand is we need to start visiting the top level node in sequence and stop when we get node expect the assignment node and thing like visitor would help in traversing top level nodes or Maybe there would be is a simpler solution which I am unable to see. OpenSCAD support is now provided by the Mailing List. I have a problem with If statement in OpenScad. They are not really constants either, because they can be overridden locally within inner scopes. If these were intended to be reassignable variables, then there would need to be a way to conditionally modify a variable inside of an if statement, and there isn't. since it seems in fashion to point out personal #1 turnoffs, this is mine: O> I beg to differ. Other OSs and Versions. An openscad variable only has one value during the life of the program. It would also provide the compile time datastructure that we need to implement namespaces. It uses sequential scoping, as proposed by Oskar. Let's say that the syntax of an anonymous function expression is. One other option is to disable all use of function variables if any conflicting name is detected. Illegal assignment from List to List, Substituting black beans for ground beef in a meat pie. So far so good. If the warning showed a file and line number it would be much clearer. The compiler needs to keep track of which source file a definition came from, so that it can report errors and implement scoping rules, and the current implementation throws away this information. In openscad you can use the ? We don't process 'include' statements at parse time, we process them at compile time. So what mental model should we use for "assignment statements"? This is a 'recursive' let, in which all bindings are visible in all definitions. In OpenSCAD, you cannot re-change the value of a variable. Then we take the results of compiling the included file, and we insert those definitions and geometry statements into the parent context, which has also been compiled. E.g. They look like they are variables, but a "variable" can only have one value in the run of the program, the value of the last assignment. Adding one more might be odd, but it would be less painful than the current situation of allowing such errors to pass silently. Then pick the interpreter to use, as a run-time option. And it's true, but this leads to nasty surprises. I am trying to update the variable within the loop. And after depending who is smaller to take the value of smaller variable(in our case b < a) and to make a simple operation with c variable ( c=b-w). Eg, 'x = 2' is like 'const x = 2' in C++. The last variable assignment within a scope applies everywhere in that scope. 2. Eg, 'x = 2' is like 'const x = 2' in C++. Once we have banned duplicate definitions, it now becomes possible to define a consistent set of scoping rules. OpenSCAD support is now provided by the Mailing List. Once we have this syntax, then I think the following two statements should be equivalent: I'd like function definitions to work in any scope, and to support recursion. OpenSCAD is a free open source software for the creation of three-dimensional geometries. As for your above code, you can use the following code to achieve your goal. Not the answer you're looking for? According to the user manual, "include acts as if the contents of the included file were written in the including file". It is simply the line "assign(x=f(x))" uses the only x that is in scope at that point, which is x=1. In summary, I'm endorsing Oskar's proposal to implement a 'let' expression with sequential scoping. So this kind of thing works in any { } enclosed statement block: a = b; // local definition of 'a'. Re-assigning values to "variables" Classic List Threaded 7 messages Options function genv(f, i, l) = f > l ? Follow asked Jun 26, 2016 at 12:49. handle handle. I don't see how a checkbox and warnings would help. What is OpenSCAD? I can define a variable at the top level, and it has global scope. doesn't "c = min(a,b) -w" match your question? http://rocklinux.net/mailman/listinfo/openscad, http://forum.openscad.org/Variable-assignment-expression-tp7670p8345.html, http://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Manual/Conditional_and_Iterator_Functions#If_Statement, http://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Include_Statement, http://forum.openscad.org/Variable-assignment-expression-tp7670p8374.html, http://forum.openscad.org/Variable-assignment-expression-tp7670p8395.html. Nabble removed Mailing-list integration from the Forum. There are instructions on how to override definitions in an included file, but the process is inherently confusing. That is the greatest hack ever. It turns out that function definitions and module definitions have the same semantics. On Sat, Nov 22, 2014 at 11:25 AM, Marius Kintel. 1. Once we do this, it will then be possible to define named functions within a local scope, at either the expression or module level, using the syntactic extensions Oskar discusses. The for loop works through the "outer" array and pulls out each point in turn, translates to that position and puts a cylinder there. Set variables to a new value for a sub-tree. include interacted, the lib.scad/hello.scad example didn't make any. Chapter 1: A few words about OpenSCAD and getting started with the first object. b = a + 1; // local 'a' is in the scope of the definition of 'b'. Printables Basics Buyer's Guides Reviews Deals. Or if that is too easy, the full version is available here: OpenSCAD support is now provided by the Mailing List. I haven't made up my mind on the proposal yet tho (but adding complexity to one of OpenSCAD strengths, simplicity), I think the example is easier to read without using let or the undefined. . Regarding the reporting line numbers bug. If you find a variable that is not a function reference then ignore it and treat it as calling an undefined function. which is the conditional assignment of variables. your conditions: OpenSCAD's variable assignment is different. While experimenting with it, I substituted the contents of lib.scad. The ML family of languages support 'let' and 'let rec' (but not sequential let). If we disallow duplication definitions within the same source file, but we preserve backwards compatibility and allow you to override a definition inherited from an included library file, then the 'include' statement cannot be implemented by blind textual substitution. The quoted text makes sense if you are using the email interface, but does't when it is converted to a forum format. It doesn't promote the absence of warnings for duplicate module definitions as a feature. My response is that the meaning of this program fragment should not be controversial, because the OpenSCAD implementation already provides an answer for what it should do. Making statements based on opinion; back them up with references or personal experience. This killed the Forum. This uses the scoping rules of 'sequential let'. j only needs to be defined before because it is missing a definition in the library but the library uses it. I think it's important to support backward compatibility, so that (eg) the vast majority of OpenSCAD files on thingiverse do not break, and so that including existing standard library files doesn't break. Of course, choosing the language version scheme does not free one of having to do some language design in beforehand, and not just start implementing ideas ad-hoc and monkey-patching the language, or else the new version turns out to have similar inconsistencies and quirks as the current one. OpenSCAD Chat: #openscad (on IRC network libera.chat) Open SCAD is software for creating solid 3D CAD objects. When a function is called look for a function first and if that fails look for a variable that has been assigned a function reference. This isn't rocket science, it's just standard industry best practice for how to solve this particular problem, and it's how most programming languages already work. By setting OMP_NUM_THREADS environment variable to suitable number in the same shell I start FreeCAD Calculix automatically becomes multi-threaded regardless of FreeCAD's configuration.. "/> teen xxx sex pics. Not implemented yet. [2] We could preserve the essentially functional character of OpenSCAD, and reformulate "assignment statements" as definitions of named constants, so that these definitions work just like definitions in a functional language. I agree with nophead that if a source file uses a variable that isn't defined, then it's a bug in that source file. Then I have to divide this number by each value in the column v. The smallest result there shows me which row is the pivot row so I have the element. On the OpenSCAD command line, you can write 'openscad -Dname=val filename', and this overrides one or more top-level definitions in the specified file. So c = b - w will only be assigned inside the if bracket. More than one -D option can be given.
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