Resolved conflicts with master.

arrays.scad

@@ -145,18 +145,59 @@ function last(list) =
     list[len(list)-1];
 
 
-// Function: delete_last()
+// Function: list_head()
 // Usage:
-//   list = delete_last(list);
+//   list = list_head(list,<to>);
 // Topics: List Handling
-// See Also: select(), slice(), subindex(), last()
+// See Also: select(), slice(), list_tail(), last()
 // Description:
-//   Returns a list with all but the last entry from the input list.  If input is empty, returns empty list.
+//   Returns the head of the given list, from the first item up until the `to` index, inclusive.
-// Example:
+//   If the `to` index is negative, then the length of the list is added to it, such that
-//   nlist = delete_last(["foo", "bar", "baz"]);  // Returns: ["foo", "bar"]
+//   `-1` is the last list item.  `-2` is the second from last.  `-3` is third from last, etc.
-function delete_last(list) =
+//   If the list is shorter than the given index, then the full list is returned.
+// Arguments:
+//   list = The list to get the head of.
+//   to = The last index to include.  If negative, adds the list length to it.  ie: -1 is the last list item.
+// Examples:
+//   hlist = list_head(["foo", "bar", "baz"]);  // Returns: ["foo", "bar"]
+//   hlist = list_head(["foo", "bar", "baz"], -3); // Returns: ["foo"]
+//   hlist = list_head(["foo", "bar", "baz"], 2);  // Returns: ["foo","bar"]
+//   hlist = list_head(["foo", "bar", "baz"], -5); // Returns: []
+//   hlist = list_head(["foo", "bar", "baz"], 5);  // Returns: ["foo","bar","baz"]
+function list_head(list, to=-2) =
    assert(is_list(list))
-   list==[] ? [] : slice(list,0,-2);
+   assert(is_finite(to))
+   to<0? [for (i=[0:1:len(list)+to]) list[i]] :
+   to<len(list)? [for (i=[0:1:to]) list[i]] :
+   list;
+
+
+// Function: list_tail()
+// Usage:
+//   list = list_tail(list,<from>);
+// Topics: List Handling
+// See Also: select(), slice(), list_tail(), last()
+// Description:
+//   Returns the tail of the given list, from the `from` index up until the end of the list, inclusive.
+//   If the `from` index is negative, then the length of the list is added to it, such that
+//   `-1` is the last list item.  `-2` is the second from last.  `-3` is third from last, etc.
+//   If you want it to return the last three items of the list, use `from=-3`.
+// Arguments:
+//   list = The list to get the tail of.
+//   from = The first index to include.  If negative, adds the list length to it.  ie: -1 is the last list item.
+// Examples:
+//   tlist = list_tail(["foo", "bar", "baz"]);  // Returns: ["bar", "baz"]
+//   tlist = list_tail(["foo", "bar", "baz"], -1); // Returns: ["baz"]
+//   tlist = list_tail(["foo", "bar", "baz"], 2);  // Returns: ["baz"]
+//   tlist = list_tail(["foo", "bar", "baz"], -5); // Returns: ["foo","bar","baz"]
+//   tlist = list_tail(["foo", "bar", "baz"], 5);  // Returns: []
+function list_tail(list, from=1) =
+   assert(is_list(list))
+   assert(is_finite(from))
+   from>=0? [for (i=[from:1:len(list)-1]) list[i]] :
+   let(from = from + len(list))
+   from>=0? [for (i=[from:1:len(list)-1]) list[i]] :
+   list;
 
 
 // Function: list()

beziers.scad

@@ -945,7 +945,7 @@ module bezier_polygon(bezier, splinesteps=16, N=3) {
     assert(is_int(splinesteps));
     assert(len(bezier)%N == 1, str("A degree ",N," bezier path shound have a multiple of ",N," points in it, plus 1."));
     polypoints=bezier_path(bezier, splinesteps, N);
-    polygon(points=slice(polypoints, 0, -1));
+    polygon(points=polypoints);
 }
 
 

common.scad

@@ -273,7 +273,6 @@ function is_bool_list(list, length) =
 // Topics: Undef Handling
 // See Also: first_defined(), one_defined(), num_defined()
 // Description:
-//   Returns the value given as `v` if it is not `undef`.  Otherwise, returns the value of `dflt`.
 //   Returns the value given as `v` if it is not `undef`.
 //   Otherwise, returns the value of `dflt`.
 // Arguments:
@@ -294,8 +293,7 @@ function default(v,dflt=undef) = is_undef(v)? dflt : v;
 //   v = The list whose items are being checked.
 //   recursive = If true, sublists are checked recursively for defined values.  The first sublist that has a defined item is returned.
 // Examples:
-//   list =  ***
+//   val = first_defined([undef,7,undef,true]);  // Returns: 1
-//   val = first_defined(list)
 function first_defined(v,recursive=false,_i=0) =
     _i<len(v) && (
         is_undef(v[_i]) || (
@@ -311,7 +309,6 @@ function first_defined(v,recursive=false,_i=0) =
 //   val = one_defined(vals, names, <dflt>)
 // Topics: Undef Handling
 // See Also: default(), first_defined(), num_defined(), any_defined(), all_defined()
-//   one_defined(vars, names, <required>)
 // Description:
 //   Examines the input list `vals` and returns the entry which is not `undef`.
 //   If more than one entry is not `undef` then an error is asserted, specifying
@@ -608,15 +605,15 @@ function segs(r) =
 
 
 // Module: no_children()
+// Topics: Error Checking
 // Usage:
 //   no_children($children);
-// Topics: Error Checking
-// See Also: no_function(), no_module()
 // Description:
-//   Assert that the calling module does not support children. Prints an error message to this effect 
+//   Assert that the calling module does not support children.  Prints an error message to this effect and fails if children are present,
-//   and fails if children are present, as indicated by its argument.
+//   as indicated by its argument.
 // Arguments:
 //   $children = number of children the module has.  
+// See Also: no_function(), no_module()
 // Example:
 //   module foo() {
 //       no_children($children);
@@ -679,7 +676,7 @@ function _valstr(x) =
 //   expected = The value that was expected.
 //   info = Extra info to print out to make the error clearer.
 // Example:
-//   assert_approx(1/3, 0.333333333333333, str("number=",1,", demon=",3));
+//   assert_approx(1/3, 0.333333333333333, str("numer=",1,", demon=",3));
 module assert_approx(got, expected, info) {
     no_children($children);
     if (!approx(got, expected)) {
@@ -778,8 +775,8 @@ module shape_compare(eps=1/1024) {
 //   The syntax is: `[for (INIT; CONDITION; NEXT) RETVAL]` where:
 //   - INIT is zero or more `let()` style assignments that are evaluated exactly one time, before the first loop.
 //   - CONDITION is an expression evaluated at the start of each loop.  If true, continues with the loop.
-//   - RETVAL is an expression that returns a list item at each loop beginning.
+//   - RETVAL is an expression that returns a list item for each loop.
-//   - NEXT is one or more `let()` style assignments that is evaluated for each loop.
+//   - NEXT is one or more `let()` style assignments that is evaluated at the end of each loop.
 //   .
 //   Since the INIT phase is only run once, and the CONDITION and RETVAL expressions cannot update
 //   variables, that means that only the NEXT phase can be used for iterative calculations.
@@ -824,7 +821,6 @@ function looping(state) = state < 2;
 
 // Function: loop_while()
 // Usage:
-//   state = loop_while(state, continue)
 //   state = loop_while(state, continue);
 // Topics: Iteration
 // See Also: looping(), loop_done()
@@ -843,7 +839,6 @@ function loop_while(state, continue) =
 
 // Function: loop_done()
 // Usage:
-//   loop_done(state)
 //   bool = loop_done(state);
 // Topics: Iteration
 // See Also: looping(), loop_while()

distributors.scad

@@ -303,9 +303,9 @@ module distribute(spacing=undef, sizes=undef, dir=RIGHT, l=undef)
     spc = !is_undef(l)? ((l - sum(gaps)) / ($children-1)) : default(spacing, 10);
     gaps2 = [for (gap = gaps) gap+spc];
     spos = dir * -sum(gaps2)/2;
+    spacings = cumsum([0, each gaps2]);
     for (i=[0:1:$children-1]) {
-        totspc = sum(concat([0], slice(gaps2, 0, i)));
+        $pos = spos + spacings[i] * dir;
-        $pos = spos + totspc * dir;
         $idx = i;
         translate($pos) children(i);
     }
@@ -348,9 +348,9 @@ module xdistribute(spacing=10, sizes=undef, l=undef)
     spc = !is_undef(l)? ((l - sum(gaps)) / ($children-1)) : default(spacing, 10);
     gaps2 = [for (gap = gaps) gap+spc];
     spos = dir * -sum(gaps2)/2;
+    spacings = cumsum([0, each gaps2]);
     for (i=[0:1:$children-1]) {
-        totspc = sum(concat([0], slice(gaps2, 0, i)));
+        $pos = spos + spacings[i] * dir;
-        $pos = spos + totspc * dir;
         $idx = i;
         translate($pos) children(i);
     }
@@ -393,9 +393,9 @@ module ydistribute(spacing=10, sizes=undef, l=undef)
     spc = !is_undef(l)? ((l - sum(gaps)) / ($children-1)) : default(spacing, 10);
     gaps2 = [for (gap = gaps) gap+spc];
     spos = dir * -sum(gaps2)/2;
+    spacings = cumsum([0, each gaps2]);
     for (i=[0:1:$children-1]) {
-        totspc = sum(concat([0], slice(gaps2, 0, i)));
+        $pos = spos + spacings[i] * dir;
-        $pos = spos + totspc * dir;
         $idx = i;
         translate($pos) children(i);
     }
@@ -438,9 +438,9 @@ module zdistribute(spacing=10, sizes=undef, l=undef)
     spc = !is_undef(l)? ((l - sum(gaps)) / ($children-1)) : default(spacing, 10);
     gaps2 = [for (gap = gaps) gap+spc];
     spos = dir * -sum(gaps2)/2;
+    spacings = cumsum([0, each gaps2]);
     for (i=[0:1:$children-1]) {
-        totspc = sum(concat([0], slice(gaps2, 0, i)));
+        $pos = spos + spacings[i] * dir;
-        $pos = spos + totspc * dir;
         $idx = i;
         translate($pos) children(i);
     }

geometry.scad

@@ -812,7 +812,9 @@ function adj_opp_to_ang(adj,opp) =
 //   Returns the area of a triangle formed between three 2D or 3D vertices.
 //   Result will be negative if the points are 2D and in clockwise order.
 // Arguments:
-//   a, b, c = The three vertices of the triangle.
+//   a = The first vertex of the triangle.
+//   b = The second vertex of the triangle.
+//   c = The third vertex of the triangle.
 // Examples:
 //   triangle_area([0,0], [5,10], [10,0]);  // Returns -50
 //   triangle_area([10,0], [5,10], [0,0]);  // Returns 50
@@ -881,7 +883,7 @@ function plane3pt_indexed(points, i1, i2, i3) =
 // Description:
 //   Returns a plane defined by a normal vector and a point.
 // Arguments:
-//   normal = Normal vector to the plane to find..
+//   normal = Normal vector to the plane to find.
 //   pt = Point 3D on the plane to find.
 // Example:
 //   plane_from_normal([0,0,1], [2,2,2]);  // Returns the xy plane passing through the point (2,2,2)
@@ -1905,8 +1907,8 @@ function align_polygon(reference, poly, angles, cp) =
 // Description:
 //   Given a simple 2D polygon, returns the 2D coordinates of the polygon's centroid.
 //   Given a simple 3D planar polygon, returns the 3D coordinates of the polygon's centroid.
-//   Collinear points produce an error.
+//   Collinear points produce an error.  The results are meaningless for self-intersecting
-//   The results are meaningless for self-intersecting polygons or an error is produced.
+//   polygons or an error is produced.
 // Arguments:
 //   poly = Points of the polygon from which the centroid is calculated.
 //   eps = Tolerance in geometric comparisons.  Default: `EPSILON` (1e-9)

math.scad

@@ -543,9 +543,8 @@ function _lcm(a,b) =
 
 // Computes lcm for a list of values
 function _lcmlist(a) =
-    len(a)==1 
+    len(a)==1 ? a[0] :
-    ?   a[0] 
+    _lcmlist(concat(lcm(a[0],a[1]),list_tail(a,2)));
-    :   _lcmlist(concat(slice(a,0,len(a)-2),[lcm(a[len(a)-2],a[len(a)-1])]));
 
 
 // Function: lcm()

paths.scad

@@ -885,7 +885,7 @@ function assemble_a_path_from_fragments(fragments, rightmost=true, startfrag=0,
         [outpath, newfrags]
     ) : let(
         // Path still incomplete.  Continue building it.
-        newpath = concat(path, slice(foundfrag, 1, -1)),
+        newpath = concat(path, list_tail(foundfrag)),
         newfrags = concat([newpath], remainder)
     )
     assemble_a_path_from_fragments(
@@ -1428,7 +1428,7 @@ function path_cut(path,cutdist,closed) =
       cuts = len(cutlist)
   )
   [
-      [ each slice(path,0,cutlist[0][1]),
+      [ each list_head(path,cutlist[0][1]-1),
         if (!approx(cutlist[0][0], path[cutlist[0][1]-1])) cutlist[0][0]
       ],
       for(i=[0:1:cuts-2])

regions.scad

@@ -88,7 +88,7 @@ function check_and_fix_path(path, valid_dim=undef, closed=false, name="path") =
             is_list(valid_dim) ? str("one of ",valid_dim) : valid_dim
         )
     )
-    closed && approx(path[0],select(path,-1))? slice(path,0,-2) : path;
+    closed && approx(path[0], last(path))? list_head(path) : path;
 
 
 // Function: cleanup_region()

rounding.scad

@@ -413,7 +413,7 @@ function _rounding_offsets(edgespec,z_dir=1) =
         assert(argsOK,str("Invalid specification with type ",edgetype))
         let(
                 offsets =
-                        edgetype == "profile"? scale([-1,z_dir], p=slice(points,1,-1)) :
+                        edgetype == "profile"? scale([-1,z_dir], p=list_tail(points)) :
                         edgetype == "chamfer"?  chamf_width==0 && chamf_height==0? [] : [[-chamf_width,z_dir*abs(chamf_height)]] :
                         edgetype == "teardrop"? (
                                 radius==0? [] : concat(

shapes2d.scad

@@ -851,7 +851,7 @@ function _turtle_command(command, parm, parm2, state, index) =
         )
         list_set(
             state, [path,step], [
-                concat(state[path], slice(arcpath,1,-1)),
+                concat(state[path], list_tail(arcpath)),
                 rot(lrsign * myangle,p=state[step],planar=true)
             ]
         ) :
@@ -877,7 +877,7 @@ function _turtle_command(command, parm, parm2, state, index) =
         )
         list_set(
             state, [path,step], [
-                concat(state[path], slice(arcpath,1,-1)),
+                concat(state[path], list_tail(arcpath)),
                 rot(delta_angle,p=state[step],planar=true)
             ]
         ) :

tests/test_arrays.scad

@@ -48,24 +48,33 @@ module test_last() {
 }
 test_last();
 
-module test_delete_last() {
+
+module test_list_head() {
     list = [1,2,3,4];
-    assert(delete_last(list) == [1,2,3]);
+    assert_equal(list_head(list), [1,2,3]);
-    assert(delete_last([1]) == []);
+    assert_equal(list_head([1]), []);
-    assert(delete_last([]) == []);
+    assert_equal(list_head([]), []);
+    assert_equal(list_head(list,-3), [1,2]);
+    assert_equal(list_head(list,1), [1,2]);
+    assert_equal(list_head(list,2), [1,2,3]);
+    assert_equal(list_head(list,6), [1,2,3,4]);
+    assert_equal(list_head(list,-6), []);
 }
-test_delete_last();
+test_list_head();
 
 
-module test_slice() {
+module test_list_tail() {
-    assert(slice([3,4,5,6,7,8,9], 3, 5) == [6,7]);
+    list = [1,2,3,4];
-    assert(slice([3,4,5,6,7,8,9], 2, -1) == [5,6,7,8,9]);
+    assert_equal(list_tail(list), [2,3,4]);
-    assert(slice([3,4,5,6,7,8,9], 1, 1) == []);
+    assert_equal(list_tail([1]), []);
-    assert(slice([3,4,5,6,7,8,9], 6, -1) == [9]);
+    assert_equal(list_tail([]), []);
-    assert(slice([3,4,5,6,7,8,9], 2, -2) == [5,6,7,8]);
+    assert_equal(list_tail(list,-3), [2,3,4]);
-    assert(slice([], 2, -2) == []);
+    assert_equal(list_tail(list,2), [3,4]);
+    assert_equal(list_tail(list,3), [4]);
+    assert_equal(list_tail(list,6), []);
+    assert_equal(list_tail(list,-6), [1,2,3,4]);
 }
-test_slice();
+test_list_tail();
 
 
 module test_in_list() {

turtle3d.scad

@@ -540,28 +540,28 @@ function _turtle3d_command(command, parm, parm2, state, index) =
     command=="addlength" ?  list_set(state, movestep, state[movestep]+parm) :
     command=="arcsteps" ?  assert(is_int(parm) && parm>0, str("\"",command,"\" requires a postive integer argument at index ",index))
                            list_set(state, arcsteps, parm) :
-    command=="roll" ? list_set(state, trlist, concat(slice(state[trlist],0,-2), [lastT*xrot(parm)])):
+    command=="roll" ? list_set(state, trlist, concat(list_head(state[trlist]), [lastT*xrot(parm)])):
     in_list(command,["right","left","up","down"]) ? 
-        list_set(state, trlist, concat(slice(state[trlist],0,-2), [lastT*_turtle3d_rotation(command,default(parm,state[angle]))])):
+        list_set(state, trlist, concat(list_head(state[trlist]), [lastT*_turtle3d_rotation(command,default(parm,state[angle]))])):
     in_list(command,["xrot","yrot","zrot"]) ?
         let(
              Trot = _rotpart(lastT),      // Extract rotational part of lastT
              shift = _transpart(lastT)    // Translation part of lastT
         )
-        list_set(state, trlist, concat(slice(state[trlist],0,-2),
+        list_set(state, trlist, concat(list_head(state[trlist]),
                                        [move(shift)*_turtle3d_rotation(command,default(parm,state[angle])) * Trot])):
     command=="rot" ?
         let(
              Trot = _rotpart(lastT),      // Extract rotational part of lastT
              shift = _transpart(lastT)    // Translation part of lastT
         )
-        list_set(state, trlist, concat(slice(state[trlist],0,-2),[move(shift) * parm * Trot])):
+        list_set(state, trlist, concat(list_head(state[trlist]),[move(shift) * parm * Trot])):
     command=="setdir" ?
         let(
              Trot = _rotpart(lastT),
              shift = _transpart(lastT)
         )
-        list_set(state, trlist, concat(slice(state[trlist],0,-2),
+        list_set(state, trlist, concat(list_head(state[trlist]),
                                        [move(shift)*rot(from=apply(Trot,RIGHT),to=parm) * Trot ])):
     in_list(command,["arcleft","arcright","arcup","arcdown"]) ?
         assert(is_num(parm),str("\"",command,"\" command requires a numeric radius value at index ",index))